This problem has been plaguing me since the official release of 11.04
I'm starting to get fed up with it!! 
I have tried: 
Update install of 11.04
Clean install of 11.04
CCSM: disable sync to vblank
Updating fglxr to manufacturer update
Compiz fusion: set metacity as window manager
Purging fglxr entirely 
disabling screensaver ( results in system freeze after 15-20 min)

Here is a detailed list of my system. Sorry if it's too verbose, but maybe it will be helpful.
description: Computer
    width: 32 bits
    capabilities: smbios-2.3 dmi-2.3 smp-1.4 smp
    configuration: boot=normal cpus=1 uuid=E5947731-AA18-11DA-B2D4-0013D47AA8E1
  *-core
       description: Motherboard
       product: D945GNT
       vendor: Intel Corporation
       physical id: 0
       version: AAC96315-404
       serial: AZNT61007123
       slot: Base Board Chassis Location
     *-cpu
          description: CPU
          product: Intel(R) Pentium(R) 4 CPU 3.00GHz
          vendor: Intel Corp.
          physical id: 0
          bus info: cpu@0
          version: 15.4.3
          serial: 0000-0F43-0000-0000-0000-0000
          slot: J3E1
          size: 2800MHz
          capacity: 4GHz
          width: 64 bits
          clock: 200MHz
          capabilities: boot fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx x86-64 constant_tsc pebs bts pni dtes64 monitor ds_cpl est cid cx16 xtpr cpufreq
          configuration: id=0
        *-cache:0
             description: L1 cache
             physical id: 1
             slot: Unknown
             size: 16KiB
             capacity: 16KiB
             capabilities: asynchronous internal write-back data
        *-cache:1
             description: L2 cache
             physical id: 2
             slot: Unknown
             size: 2MiB
             capacity: 2MiB
             capabilities: asynchronous internal write-back unified
        *-logicalcpu:0
             description: Logical CPU
             physical id: 0.1
             width: 64 bits
             capabilities: logical
        *-logicalcpu:1
             description: Logical CPU
             physical id: 0.2
             width: 64 bits
             capabilities: logical
     *-firmware
          description: BIOS
          vendor: Intel Corp.
          physical id: 3
          version: NT94510J.86A.3239.2005.1205.1900
          date: 12/05/2005
          size: 64KiB
          capacity: 448KiB
          capabilities: pci upgrade shadowing cdboot bootselect edd int9keyboard int14serial int17printer int10video acpi usb zipboot biosbootspecification netboot
     *-memory
          description: System Memory
          physical id: 16
          slot: System board or motherboard
          size: 4GiB
        *-bank:0
             description: DIMM DDR2 Synchronous 400 MHz (2.5 ns)
             vendor: Kingston
             physical id: 0
             serial: 0x3D22D7F9
             slot: J6H1
             size: 1GiB
             width: 64 bits
             clock: 400MHz (2.5ns)
        *-bank:1
             description: DIMM DDR2 Synchronous 400 MHz (2.5 ns)
             vendor: Kingston
             physical id: 1
             serial: 0x3C23EB26
             slot: J6H2
             size: 1GiB
             width: 64 bits
             clock: 400MHz (2.5ns)
        *-bank:2
             description: DIMM DDR2 Synchronous 400 MHz (2.5 ns)
             vendor: Kingston
             physical id: 2
             serial: 0x3F23E426
             slot: J6J1
             size: 1GiB
             width: 64 bits
             clock: 400MHz (2.5ns)
        *-bank:3
             description: DIMM DDR2 Synchronous 400 MHz (2.5 ns)
             vendor: Kingston
             physical id: 3
             serial: 0x3D22CEF9
             slot: J6J2
             size: 1GiB
             width: 64 bits
             clock: 400MHz (2.5ns)
     *-pci
          description: Host bridge
          product: 82945G/GZ/P/PL Memory Controller Hub
          vendor: Intel Corporation
          physical id: 100
          bus info: pci@0000:00:00.0
          version: 02
          width: 32 bits
          clock: 33MHz
        *-pci:0
             description: PCI bridge
             product: 82945G/GZ/P/PL PCI Express Root Port
             vendor: Intel Corporation
             physical id: 1
             bus info: pci@0000:00:01.0
             version: 02
             width: 32 bits
             clock: 33MHz
             capabilities: pci pm msi pciexpress normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:40 ioport:2000(size=4096) memory:e4300000-e43fffff ioport:d0000000(size=268435456)
           *-display
                description: VGA compatible controller
                product: Mobility Radeon HD 3600 Series
                vendor: ATI Technologies Inc
                physical id: 0
                bus info: pci@0000:01:00.0
                version: 00
                width: 64 bits
                clock: 33MHz
                capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
                configuration: driver=fglrx_pci latency=0
                resources: irq:46 memory:d0000000-dfffffff memory:e4300000-e430ffff ioport:2000(size=256) memory:e4320000-e433ffff
           *-multimedia
                description: Audio device
                product: RV635 Audio device [Radeon HD 3600 Series]
                vendor: ATI Technologies Inc
                physical id: 0.1
                bus info: pci@0000:01:00.1
                version: 00
                width: 64 bits
                clock: 33MHz
                capabilities: pm pciexpress msi bus_master cap_list
                configuration: driver=HDA Intel latency=0
                resources: irq:45 memory:e4310000-e4313fff
        *-multimedia
             description: Audio device
             product: N10/ICH 7 Family High Definition Audio Controller
             vendor: Intel Corporation
             physical id: 1b
             bus info: pci@0000:00:1b.0
             version: 01
             width: 64 bits
             clock: 33MHz
             capabilities: pm msi pciexpress bus_master cap_list
             configuration: driver=HDA Intel latency=0
             resources: irq:44 memory:e4400000-e4403fff
        *-pci:1
             description: PCI bridge
             product: N10/ICH 7 Family PCI Express Port 1
             vendor: Intel Corporation
             physical id: 1c
             bus info: pci@0000:00:1c.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:41 ioport:4000(size=4096) memory:e4500000-e45fffff ioport:e4800000(size=2097152)
        *-pci:2
             description: PCI bridge
             product: N10/ICH 7 Family PCI Express Port 3
             vendor: Intel Corporation
             physical id: 1c.2
             bus info: pci@0000:00:1c.2
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:42 ioport:5000(size=4096) memory:e4600000-e46fffff ioport:e4a00000(size=2097152)
        *-pci:3
             description: PCI bridge
             product: N10/ICH 7 Family PCI Express Port 4
             vendor: Intel Corporation
             physical id: 1c.3
             bus info: pci@0000:00:1c.3
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:43 ioport:6000(size=4096) memory:e4700000-e47fffff ioport:e4c00000(size=2097152)
        *-usb:0
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #1
             vendor: Intel Corporation
             physical id: 1d
             bus info: pci@0000:00:1d.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:23 ioport:3080(size=32)
        *-usb:1
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #2
             vendor: Intel Corporation
             physical id: 1d.1
             bus info: pci@0000:00:1d.1
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:19 ioport:3060(size=32)
        *-usb:2
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #3
             vendor: Intel Corporation
             physical id: 1d.2
             bus info: pci@0000:00:1d.2
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:18 ioport:3040(size=32)
        *-usb:3
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #4
             vendor: Intel Corporation
             physical id: 1d.3
             bus info: pci@0000:00:1d.3
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:16 ioport:3020(size=32)
        *-usb:4
             description: USB Controller
             product: N10/ICH 7 Family USB2 EHCI Controller
             vendor: Intel Corporation
             physical id: 1d.7
             bus info: pci@0000:00:1d.7
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pm debug ehci bus_master cap_list
             configuration: driver=ehci_hcd latency=0
             resources: irq:23 memory:e4404000-e44043ff
        *-pci:4
             description: PCI bridge
             product: 82801 PCI Bridge
             vendor: Intel Corporation
             physical id: 1e
             bus info: pci@0000:00:1e.0
             version: e1
             width: 32 bits
             clock: 33MHz
             capabilities: pci subtractive_decode bus_master cap_list
             resources: ioport:1000(size=4096) memory:e0000000-e42fffff
           *-multimedia
                description: Multimedia audio controller
                product: SB X-Fi
                vendor: Creative Labs
                physical id: 2
                bus info: pci@0000:05:02.0
                version: 00
                width: 64 bits
                clock: 33MHz
                capabilities: pm msi bus_master cap_list
                configuration: driver=SB-XFi latency=32 maxlatency=5 mingnt=4
                resources: irq:18 ioport:1040(size=32) memory:e4000000-e41fffff memory:e0000000-e3ffffff
           *-network
                description: Ethernet interface
                product: N10/ICH 7 Family LAN Controller
                vendor: Intel Corporation
                physical id: 8
                bus info: pci@0000:05:08.0
                logical name: eth0
                version: 01
                serial: 00:16:76:38:14:64
                size: 100Mbit/s
                capacity: 100Mbit/s
                width: 32 bits
                clock: 33MHz
                capabilities: pm bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
                configuration: autonegotiation=on broadcast=yes driver=e100 driverversion=3.5.24-k2-NAPI duplex=full firmware=N/A ip=192.168.1.102 latency=32 link=yes maxlatency=56 mingnt=8 multicast=yes port=MII speed=100Mbit/s
                resources: irq:20 memory:e4200000-e4200fff ioport:1000(size=64)
        *-isa
             description: ISA bridge
             product: 82801GB/GR (ICH7 Family) LPC Interface Bridge
             vendor: Intel Corporation
             physical id: 1f
             bus info: pci@0000:00:1f.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: isa bus_master cap_list
             configuration: latency=0
        *-ide:0
             description: IDE interface
             product: 82801G (ICH7 Family) IDE Controller
             vendor: Intel Corporation
             physical id: 1f.1
             bus info: pci@0000:00:1f.1
             logical name: scsi0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: ide bus_master emulated
             configuration: driver=ata_piix latency=0
             resources: irq:18 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:30b0(size=16)
           *-cdrom:0
                description: DVD writer
                product: CD/DVDW SD-R5372
                vendor: TOSHIBA
                physical id: 0.0.0
                bus info: scsi@0:0.0.0
                logical name: /dev/cdrom1
                logical name: /dev/cdrw1
                logical name: /dev/dvd1
                logical name: /dev/dvdrw1
                logical name: /dev/scd0
                logical name: /dev/sr0
                version: TU53
                capabilities: removable audio cd-r cd-rw dvd dvd-r
                configuration: ansiversion=5 status=nodisc
           *-cdrom:1
                description: SCSI CD-ROM
                physical id: 0.1.0
                bus info: scsi@0:0.1.0
                logical name: /dev/cdrom
                logical name: /dev/scd1
                logical name: /dev/sr1
                capabilities: audio
                configuration: status=nodisc
        *-ide:1
             description: IDE interface
             product: N10/ICH7 Family SATA IDE Controller
             vendor: Intel Corporation
             physical id: 1f.2
             bus info: pci@0000:00:1f.2
             logical name: scsi2
             logical name: scsi3
             version: 01
             width: 32 bits
             clock: 66MHz
             capabilities: ide pm bus_master cap_list emulated
             configuration: driver=ata_piix latency=0
             resources: irq:19 ioport:30c8(size=8) ioport:30e4(size=4) ioport:30c0(size=8) ioport:30e0(size=4) ioport:30a0(size=16)
           *-disk:0
                description: ATA Disk
                product: WDC WD3200AAJS-0
                vendor: Western Digital
                physical id: 0
                bus info: scsi@2:0.0.0
                logical name: /dev/sda
                version: 01.0
                serial: WD-WCAV2V043999
                size: 298GiB (320GB)
                capabilities: partitioned partitioned:dos
                configuration: ansiversion=5 signature=000c8f11
              *-volume:0
                   description: EXT4 volume
                   vendor: Linux
                   physical id: 1
                   bus info: scsi@2:0.0.0,1
                   logical name: /dev/sda1
                   logical name: /
                   version: 1.0
                   serial: 4408114b-449c-49e4-b48f-b353ceb58dd3
                   size: 279GiB
                   capacity: 279GiB
                   capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized
                   configuration: created=2011-05-16 23:27:53 filesystem=ext4 lastmountpoint=/ modified=2011-05-16 23:51:03 mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered mounted=2011-05-22 20:45:56 state=mounted
              *-volume:1
                   description: Extended partition
                   physical id: 2
                   bus info: scsi@2:0.0.0,2
                   logical name: /dev/sda2
                   size: 18GiB
                   capacity: 18GiB
                   capabilities: primary extended partitioned partitioned:extended
                 *-logicalvolume
                      description: Linux swap / Solaris partition
                      physical id: 5
                      logical name: /dev/sda5
                      capacity: 18GiB
                      capabilities: nofs
           *-disk:1
                description: ATA Disk
                product: WDC WD3200AAJS-0
                vendor: Western Digital
                physical id: 1
                bus info: scsi@3:0.0.0
                logical name: /dev/sdb
                version: 01.0
                serial: WD-WCAV2V043804
                size: 298GiB (320GB)
                capabilities: partitioned partitioned:dos
                configuration: ansiversion=5 signature=95349534
              *-volume
                   description: EXT4 volume
                   vendor: Linux
                   physical id: 1
                   bus info: scsi@3:0.0.0,1
                   logical name: /dev/sdb1
                   version: 1.0
                   serial: e8f9f2fc-db80-4180-91e3-663a6603d92c
                   size: 298GiB
                   capacity: 298GiB
                   capabilities: primary journaled extended_attributes large_files huge_files dir_nlink extents ext4 ext2 initialized
                   configuration: created=2011-04-28 16:18:10 filesystem=ext4 label=StorageDATA modified=2011-04-30 09:27:27 mounted=2011-04-28 16:18:29 state=clean
        *-serial UNCLAIMED
             description: SMBus
             product: N10/ICH 7 Family SMBus Controller
             vendor: Intel Corporation
             physical id: 1f.3
             bus info: pci@0000:00:1f.3
             version: 01
             width: 32 bits
             clock: 33MHz
             configuration: latency=0
             resources: ioport:3000(size=32)
     *-scsi
          physical id: 1
          bus info: usb@1:3
          logical name: scsi4
          capabilities: emulated scsi-host
          configuration: driver=usb-storage
        *-disk
             description: SCSI Disk
             product: Photosmart C3180
             vendor: HP
             physical id: 0.0.0
             bus info: scsi@4:0.0.0
             logical name: /dev/sdc
             version: 1.00
             capabilities: removable
             configuration: ansiversion=2
           *-medium
                physical id: 0
                logical name: /dev/sdc