Hi I have it on my Mythbuntu Lucid.

It already started some weeks ago when it still was on Karmic.  The trigger for me was XBMC.   I'm not sure it's because the mythbackend/frontend is on the same machine and because it's accessing the mysql from it.  When XBMC is not started, and I only use mythfrontend it's less frequent or even not occuring.

I use spdif for the my Surround.
It's happening even when the xbmc is on it's main screen for some hours.  Only hard reset works.  No network (ssh/vnc) / keyboard or mouse works.

I see a IRQ message for my soundcard before the events happen.

May 30 11:57:40 MythMan kernel: [ 2699.932606] sd 8:0:0:0: [sdb] Write Protect is off
May 30 11:57:40 MythMan kernel: [ 2699.937433]  sdb: sdb1
May 30 11:57:40 MythMan kernel: [ 2699.961431] sd 8:0:0:0: [sdb] Attached SCSI disk
May 30 11:57:45 MythMan kernel: [ 2704.685371] hda-intel: IRQ timing workaround is activated for card #0. Suggest a bigger bdl_pos_adj.
May 30 14:04:43 MythMan pulseaudio[2234]: ratelimit.c: 394 events suppressed
May 30 16:12:16 MythMan pulseaudio[2234]: ratelimit.c: 181 events suppressed
May 30 18:44:41 MythMan pulseaudio[2234]: ratelimit.c: 228 events suppressed
May 30 19:45:42 MythMan pulseaudio[2234]: ratelimit.c: 221 events suppressed
May 30 19:48:47 MythMan pulseaudio[2234]: ratelimit.c: 300 events suppressed
May 30 19:57:19 MythMan pulseaudio[2234]: ratelimit.c: 230 events suppressed
May 30 20:01:40 MythMan pulseaudio[2234]: ratelimit.c: 226 events suppressed
May 30 20:23:26 MythMan pulseaudio[2234]: ratelimit.c: 221 events suppressed
May 30 20:40:27 MythMan pulseaudio[2234]: ratelimit.c: 222 events suppressed
May 30 20:56:53 MythMan kernel: imklog 4.2.0, log source = /proc/kmsg started.


This is my card 0

00:10.1 Audio device [0403]: nVidia Corporation MCP51 High Definition Audio [10de:026c] (rev a2)
        Subsystem: Micro-Star International Co., Ltd. Device [1462:3290]
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0 (500ns min, 1250ns max)
        Interrupt: pin B routed to IRQ 22
        Region 0: Memory at fead8000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: [44] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [50] Message Signalled Interrupts: Mask+ 64bit+ Queue=0/0 Enable-
                Address: 0000000000000000  Data: 0000
                Masking: 00000000  Pending: 00000000
        Capabilities: [6c] HyperTransport: MSI Mapping Enable- Fixed+
        Kernel driver in use: HDA Intel
        Kernel modules: snd-hda-intel


mythman
    description: Desktop Computer
    product: MS-7329
    vendor: MSI
    version: 2.0
    serial: To Be Filled By O.E.M.
    width: 64 bits
    capabilities: smbios-2.4 dmi-2.4 vsyscall64 vsyscall32
    configuration: chassis=desktop uuid=00020003-0004-0005-0006-000700080009
  *-core
       description: Motherboard
       product: MS-7329
       vendor: MSI
       physical id: 0
       version: 2.0
       serial: To be filled by O.E.M.
       slot: To Be Filled By O.E.M.
     *-firmware
          description: BIOS
          vendor: American Megatrends Inc.
          physical id: 0
          version: 080013 (08/20/2008)
          size: 64KiB
          capacity: 448KiB
          capabilities: pci pnp apm upgrade shadowing escd cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb biosbootspecification
     *-cpu
          description: CPU
          product: AMD Athlon(tm) 64 X2 Dual Core Processor 5000+
          vendor: Advanced Micro Devices [AMD]
          physical id: 1
          bus info: cpu@0
          version: AMD Athlon(tm) 64 X2 Dual Core Processor 5000+
          serial: To Be Filled By O.E.M.
          slot: CPU 1
          size: 1GHz
          capacity: 2600MHz
          width: 64 bits
          clock: 200MHz
          capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp x86-64 3dnowext 3dnow rep_good extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch cpufreq
        *-cache:0
             description: L1 cache
             physical id: 5
             slot: L1-Cache
             size: 128KiB
             capacity: 128KiB
             capabilities: pipeline-burst internal varies data
        *-cache:1
             description: L2 cache
             physical id: 6
             slot: L2-Cache
             size: 1MiB
             capacity: 1MiB
             capabilities: pipeline-burst internal varies unified
     *-memory:0
          description: System Memory
          physical id: 27
          slot: System board or motherboard
          size: 1GiB
        *-bank:0
             description: DIMM DDR2 Synchronous 266 MHz (3.8 ns)
             product: PartNum0
             vendor: Manufacturer0
             physical id: 0
             serial: SerNum0
             slot: DIMM0
             size: 1GiB
             width: 64 bits
             clock: 266MHz (3.8ns)
        *-bank:1
             description: DIMM [empty]
             product: PartNum1
             vendor: Manufacturer1
             physical id: 1
             serial: SerNum1
             slot: DIMM1
        *-bank:2
             description: DIMM [empty]
             product: PartNum2
             vendor: Manufacturer2
             physical id: 2
             serial: SerNum2
             slot: DIMM2
        *-bank:3
             description: DIMM [empty]
             product: PartNum3
             vendor: Manufacturer3
             physical id: 3
             serial: SerNum3
             slot: DIMM3
     *-memory:1 UNCLAIMED
          description: RAM memory
          product: C51 Host Bridge
          vendor: nVidia Corporation
          physical id: 4
          bus info: pci@0000:00:00.0
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          capabilities: ht bus_master cap_list
          configuration: latency=0
     *-memory:2 UNCLAIMED
          description: RAM memory
          product: C51 Memory Controller 1
          vendor: nVidia Corporation
          physical id: 0.2
          bus info: pci@0000:00:00.2
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          configuration: latency=0
     *-memory:3 UNCLAIMED
          description: RAM memory
          product: C51 Memory Controller 5
          vendor: nVidia Corporation
          physical id: 0.3
          bus info: pci@0000:00:00.3
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          configuration: latency=0
     *-memory:4 UNCLAIMED
          description: RAM memory
          product: C51 Memory Controller 4
          vendor: nVidia Corporation
          physical id: 0.4
          bus info: pci@0000:00:00.4
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          capabilities: bus_master
          configuration: latency=0
     *-memory:5 UNCLAIMED
          description: RAM memory
          product: C51 Host Bridge
          vendor: nVidia Corporation
          physical id: 0.5
          bus info: pci@0000:00:00.5
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          capabilities: bus_master cap_list
          configuration: latency=0
     *-memory:6 UNCLAIMED
          description: RAM memory
          product: C51 Memory Controller 3
          vendor: nVidia Corporation
          physical id: 0.6
          bus info: pci@0000:00:00.6
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          configuration: latency=0
     *-memory:7 UNCLAIMED
          description: RAM memory
          product: C51 Memory Controller 2
          vendor: nVidia Corporation
          physical id: 0.7
          bus info: pci@0000:00:00.7
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          configuration: latency=0
     *-pci:0
          description: PCI bridge
          product: C51 PCI Express Bridge
          vendor: nVidia Corporation
          physical id: 2
          bus info: pci@0000:00:02.0
          version: a1
          width: 32 bits
          clock: 33MHz
          capabilities: pci pm msi ht pciexpress bus_master cap_list
          configuration: driver=pcieport
          resources: irq:24
     *-pci:1
          description: PCI bridge
          product: C51 PCI Express Bridge
          vendor: nVidia Corporation
          physical id: 3
          bus info: pci@0000:00:03.0
          version: a1
          width: 32 bits
          clock: 33MHz
          capabilities: pci pm msi ht pciexpress bus_master cap_list
          configuration: driver=pcieport
          resources: irq:25
     *-pci:2
          description: PCI bridge
          product: C51 PCI Express Bridge
          vendor: nVidia Corporation
          physical id: 100
          bus info: pci@0000:00:04.0
          version: a1
          width: 32 bits
          clock: 33MHz
          capabilities: pci pm msi ht pciexpress bus_master cap_list
          configuration: driver=pcieport
          resources: irq:26
     *-display
          description: VGA compatible controller
          product: C51 [GeForce 6150 LE]
          vendor: nVidia Corporation
          physical id: 5
          bus info: pci@0000:00:05.0
          version: a2
          width: 64 bits
          clock: 66MHz
          capabilities: pm msi bus_master cap_list rom
          configuration: driver=nvidia latency=0
          resources: irq:18 memory:fd000000-fdffffff memory:d0000000-dfffffff(prefetchable) memory:fc000000-fcffffff memory:feae0000-feafffff(prefetchable)
     *-memory:8 UNCLAIMED
          description: RAM memory
          product: MCP51 Host Bridge
          vendor: nVidia Corporation
          physical id: 9
          bus info: pci@0000:00:09.0
          version: a2
          width: 32 bits
          clock: 66MHz (15.2ns)
          capabilities: ht bus_master cap_list
          configuration: latency=0
     *-isa
          description: ISA bridge
          product: MCP51 LPC Bridge
          vendor: nVidia Corporation
          physical id: a
          bus info: pci@0000:00:0a.0
          version: a3
          width: 32 bits
          clock: 66MHz
          capabilities: isa bus_master
          configuration: latency=0
     *-serial
          description: SMBus
          product: MCP51 SMBus
          vendor: nVidia Corporation
          physical id: a.1
          bus info: pci@0000:00:0a.1
          version: a3
          width: 32 bits
          clock: 66MHz
          capabilities: pm cap_list
          configuration: driver=nForce2_smbus latency=0
          resources: irq:5 ioport:5000(size=64) ioport:6000(size=64)
     *-usb:0
          description: USB Controller
          product: MCP51 USB Controller
          vendor: nVidia Corporation
          physical id: b
          bus info: pci@0000:00:0b.0
          version: a3
          width: 32 bits
          clock: 66MHz
          capabilities: pm bus_master cap_list
          configuration: driver=ohci_hcd latency=0 maxlatency=1 mingnt=3
          resources: irq:21 memory:feade000-feadefff
     *-usb:1
          description: USB Controller
          product: MCP51 USB Controller
          vendor: nVidia Corporation
          physical id: b.1
          bus info: pci@0000:00:0b.1
          version: a3
          width: 32 bits
          clock: 66MHz
          capabilities: debug pm bus_master cap_list
          configuration: driver=ehci_hcd latency=0 maxlatency=1 mingnt=3
          resources: irq:23 memory:feadfc00-feadfcff
     *-ide:0
          description: IDE interface
          product: MCP51 IDE
          vendor: nVidia Corporation
          physical id: d
          bus info: pci@0000:00:0d.0
          version: a1
          width: 32 bits
          clock: 66MHz
          capabilities: ide pm bus_master cap_list
          configuration: driver=pata_amd latency=0 maxlatency=1 mingnt=3
          resources: irq:0 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:ffa0(size=16)
     *-ide:1
          description: IDE interface
          product: MCP51 Serial ATA Controller
          vendor: nVidia Corporation
          physical id: e
          bus info: pci@0000:00:0e.0
          logical name: scsi0
          version: a1
          width: 32 bits
          clock: 66MHz
          capabilities: ide pm msi ht bus_master cap_list emulated
          configuration: driver=sata_nv latency=0 maxlatency=1 mingnt=3
          resources: irq:22 ioport:d800(size=8) ioport:d480(size=4) ioport:d400(size=8) ioport:d080(size=4) ioport:d000(size=16) memory:feadd000-feaddfff
        *-disk
             description: ATA Disk
             product: ST3500320AS
             vendor: Seagate
             physical id: 0.0.0
             bus info: scsi@0:0.0.0
             logical name: /dev/sda
             version: AD14
             serial: 5QM1W76E
             size: 465GiB (500GB)
             capabilities: partitioned partitioned:dos
             configuration: ansiversion=5 signature=000376c6
           *-volume:0
                description: EXT3 volume
                vendor: Linux
                physical id: 1
                bus info: scsi@0:0.0.0,1
                logical name: /dev/sda1
                logical name: /
                version: 1.0
                serial: 7c9224f0-6e97-4bde-adda-38da3a7f3138
                size: 11GiB
                capacity: 11GiB
                capabilities: primary bootable journaled extended_attributes large_files recover ext3 ext2 initialized
                configuration: created=2009-01-09 22:09:43 filesystem=ext3 modified=2010-05-25 11:14:41 mount.fstype=ext3 mount.options=rw,relatime,errors=remount-ro,data=ordered mounted=2010-05-30 20:56:49 state=mounted
           *-volume:1
                description: Extended partition
                physical id: 2
                bus info: scsi@0:0.0.0,2
                logical name: /dev/sda2
                size: 454GiB
                capacity: 454GiB
                capabilities: primary extended partitioned partitioned:extended
              *-logicalvolume:0
                   description: Linux swap / Solaris partition
                   physical id: 5
                   logical name: /dev/sda5
                   capacity: 972MiB
                   capabilities: nofs
              *-logicalvolume:1
                   description: Linux filesystem partition
                   physical id: 6
                   logical name: /dev/sda6
                   logical name: /var/lib
                   capacity: 453GiB
                   configuration: mount.fstype=xfs mount.options=rw,relatime,attr2,noquota state=mounted
     *-ide:2
          description: IDE interface
          product: MCP51 Serial ATA Controller
          vendor: nVidia Corporation
          physical id: f
          bus info: pci@0000:00:0f.0
          version: a1
          width: 32 bits
          clock: 66MHz
          capabilities: ide pm msi ht bus_master cap_list
          configuration: driver=sata_nv latency=0 maxlatency=1 mingnt=3
          resources: irq:23 ioport:cc00(size=8) ioport:c880(size=4) ioport:c800(size=8) ioport:c480(size=4) ioport:c400(size=16) memory:feadc000-feadcfff
     *-pci:3
          description: PCI bridge
          product: MCP51 PCI Bridge
          vendor: nVidia Corporation
          physical id: 10
          bus info: pci@0000:00:10.0
          version: a2
          width: 32 bits
          clock: 66MHz
          capabilities: pci ht bus_master cap_list
          resources: ioport:e000(size=4096) memory:feb00000-febfffff memory:f4000000-fbffffff(prefetchable)
        *-pci
             description: PCI bridge
             product: HB6 Universal PCI-PCI bridge (non-transparent mode)
             vendor: Hint Corp
             physical id: 6
             bus info: pci@0000:04:06.0
             version: 11
             width: 64 bits
             clock: 33MHz
             capabilities: pci pm hotswap bus_master cap_list
             resources: iomemory:228000f00-228000eff memory:f4000000-fbffffff(prefetchable)
           *-multimedia:0
                description: Multimedia video controller
                product: iTVC16 (CX23416) MPEG-2 Encoder
                vendor: Internext Compression Inc
                physical id: 8
                bus info: pci@0000:05:08.0
                version: 01
                width: 32 bits
                clock: 33MHz
                capabilities: pm bus_master cap_list
                configuration: driver=ivtv latency=64 maxlatency=8 mingnt=128
                resources: irq:17 memory:f8000000-fbffffff(prefetchable)
           *-multimedia:1
                description: Multimedia video controller
                product: iTVC16 (CX23416) MPEG-2 Encoder
                vendor: Internext Compression Inc
                physical id: 9
                bus info: pci@0000:05:09.0
                version: 01
                width: 32 bits
                clock: 33MHz
                capabilities: pm bus_master cap_list
                configuration: driver=ivtv latency=64 maxlatency=8 mingnt=128
                resources: irq:16 memory:f4000000-f7ffffff(prefetchable)
        *-firewire
             description: FireWire (IEEE 1394)
             product: VT6306/7/8 [Fire II(M)] IEEE 1394 OHCI Controller
             vendor: VIA Technologies, Inc.
             physical id: 8
             bus info: pci@0000:04:08.0
             version: c0
             width: 32 bits
             clock: 33MHz
             capabilities: pm bus_master cap_list
             configuration: driver=ohci1394 latency=64 maxlatency=32
             resources: irq:19 memory:febff800-febfffff ioport:ec00(size=128)
     *-multimedia
          description: Audio device
          product: MCP51 High Definition Audio
          vendor: nVidia Corporation
          physical id: 10.1
          bus info: pci@0000:00:10.1
          version: a2
          width: 32 bits
          clock: 66MHz
          capabilities: pm msi ht bus_master cap_list
          configuration: driver=HDA Intel latency=0 maxlatency=5 mingnt=2
          resources: irq:22 memory:fead8000-feadbfff
     *-bridge
          description: Ethernet interface
          product: MCP51 Ethernet Controller
          vendor: nVidia Corporation
          physical id: 14
          bus info: pci@0000:00:14.0
          logical name: eth0
          version: a3
          serial: 00:1d:92:74:2c:f1
          size: 1000000000
          capacity: 1000000000
          width: 32 bits
          clock: 66MHz
          capabilities: bridge pm bus_master cap_list ethernet physical mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
          configuration: autonegotiation=on broadcast=yes driver=forcedeth driverversion=0.64 duplex=full ip=192.168.111.4 latency=0 link=yes maxlatency=20 mingnt=1 multicast=yes port=MII speed=1GB/s
          resources: irq:20 memory:fead7000-fead7fff ioport:c080(size=8)
     *-pci:4
          description: Host bridge
          product: K8 [Athlon64/Opteron] HyperTransport Technology Configuration
          vendor: Advanced Micro Devices [AMD]
          physical id: 101
          bus info: pci@0000:00:18.0
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:5
          description: Host bridge
          product: K8 [Athlon64/Opteron] Address Map
          vendor: Advanced Micro Devices [AMD]
          physical id: 102
          bus info: pci@0000:00:18.1
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:6
          description: Host bridge
          product: K8 [Athlon64/Opteron] DRAM Controller
          vendor: Advanced Micro Devices [AMD]
          physical id: 103
          bus info: pci@0000:00:18.2
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:7
          description: Host bridge
          product: K8 [Athlon64/Opteron] Miscellaneous Control
          vendor: Advanced Micro Devices [AMD]
          physical id: 104
          bus info: pci@0000:00:18.3
          version: 00
          width: 32 bits
          clock: 33MHz
          configuration: driver=k8temp
          resources: irq:0
     *-scsi:0
          physical id: 6
          bus info: usb@1:1
          logical name: scsi4
          capabilities: emulated scsi-host
          configuration: driver=usb-storage
        *-disk
             description: SCSI Disk
             physical id: 0.0.0
             bus info: scsi@4:0.0.0
             logical name: /dev/sdb
             size: 465GiB (500GB)
             capabilities: partitioned partitioned:dos
             configuration: signature=70cb9b67
           *-volume
                description: Windows NTFS volume
                physical id: 1
                bus info: scsi@4:0.0.0,1
                logical name: /dev/sdb1
                version: 3.1
                serial: 22ba3324-7306-ca40-add2-a745dce9bb41
                size: 465GiB
                capacity: 465GiB
                capabilities: primary ntfs initialized
                configuration: clustersize=4096 created=2008-04-17 16:45:54 filesystem=ntfs state=clean
     *-scsi:1
          physical id: 7
          bus info: usb@1:5.4
          logical name: scsi7
          capabilities: emulated scsi-host
          configuration: driver=usb-storage
        *-disk:0
             description: SCSI Disk
             physical id: 0.0.0
             bus info: scsi@7:0.0.0
             logical name: /dev/sdc
        *-disk:1
             description: SCSI Disk
             physical id: 0.0.1
             bus info: scsi@7:0.0.1
             logical name: /dev/sdd
        *-disk:2
             description: SCSI Disk
             physical id: 0.0.2
             bus info: scsi@7:0.0.2
             logical name: /dev/sde
        *-disk:3
             description: SCSI Disk
             physical id: 0.0.3
             bus info: scsi@7:0.0.3
             logical name: /dev/sdf
  *-network
       description: Wireless interface
       physical id: 1
       logical name: wlan0
       serial: 00:1d:92:13:b7:d5
       capabilities: ethernet physical wireless
       configuration: broadcast=yes multicast=yes wireless=IEEE 802.11bg