I'm having a very similar problem. I just upgraded my laptop (a HP Pavillion dv5000 with HDA Intel sound) from Feisty to Gutsy. It has three keys above the keyboard to control sound (up, down, and mute). Clicking the buttons doesn't affect the volume of the sound coming out of the speakers. Playing with the volume applet also fails to change the actual volume (application-specific volume controls -- the one in Totem, for instance -- work fine, which I sort of expected).

I know that the OS knows about the button clicks, because graphically it's doing what it always did (volume bar comes up in the middle of the screen).

I can still control the volume by playing with the PCM channel.

Here's the same information the last guy gave.

andersbr@lappy486:~$ tail -2 /proc/asound/oss/sndstat 
Mixers:
0: Conexant CX20551 (Waikiki)
andersbr@lappy486:~$ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 30
  Mono:
  Front Left: Playback 30 [100%] [-1.50dB] [on]
  Front Right: Playback 30 [100%] [-1.50dB] [on]
Simple mixer control 'PCM',0
  Capabilities: pvolume pswitch
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 255
  Mono:
  Front Left: Playback 218 [85%] [-7.40dB] [on]
  Front Right: Playback 218 [85%] [-7.40dB] [on]
Simple mixer control 'Mic Bypass',0
  Capabilities: cvolume cswitch
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 30
  Front Left: Capture 26 [87%] [4.50dB] [off]
  Front Right: Capture 26 [87%] [4.50dB] [off]
Simple mixer control 'IEC958',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 14
  Front Left: Capture 10 [71%] [15.00dB] [on]
  Front Right: Capture 10 [71%] [15.00dB] [on]
Simple mixer control 'ExtMic',0
  Capabilities: cswitch cswitch-joined cswitch-exclusive
  Capture exclusive group: 0
  Capture channels: Mono
  Mono: Capture [on]
andersbr@lappy486:~$ lspci  -nv
00:00.0 0600: 8086:27a0 (rev 03)
        Subsystem: 103c:30a5
        Flags: bus master, fast devsel, latency 0
        Capabilities: <access denied>

00:02.0 0300: 8086:27a2 (rev 03) (prog-if 00 [VGA])
        Subsystem: 103c:30a5
        Flags: bus master, fast devsel, latency 0, IRQ 17
        Memory at d0200000 (32-bit, non-prefetchable) [size=512K]
        I/O ports at 1800 [size=8]
        Memory at c0000000 (32-bit, prefetchable) [size=256M]
        Memory at d0300000 (32-bit, non-prefetchable) [size=256K]
        Capabilities: <access denied>

00:02.1 0380: 8086:27a6 (rev 03)
        Subsystem: 103c:30a5
        Flags: bus master, fast devsel, latency 0
        Memory at d0280000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: <access denied>

00:1b.0 0403: 8086:27d8 (rev 01)
        Subsystem: 103c:30a5
        Flags: bus master, fast devsel, latency 0, IRQ 22
        Memory at d0340000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>

00:1c.0 0604: 8086:27d0 (rev 01) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
        Capabilities: <access denied>

00:1c.1 0604: 8086:27d2 (rev 01) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
        Capabilities: <access denied>

00:1c.2 0604: 8086:27d4 (rev 01) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=06, subordinate=06, sec-latency=0
        Memory behind bridge: 8c000000-8c0fffff
        Capabilities: <access denied>

00:1d.0 0c03: 8086:27c8 (rev 01) (prog-if 00 [UHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 21
        I/O ports at 1820 [size=32]

00:1d.1 0c03: 8086:27c9 (rev 01) (prog-if 00 [UHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 20
        I/O ports at 1840 [size=32]

00:1d.2 0c03: 8086:27ca (rev 01) (prog-if 00 [UHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 18
        I/O ports at 1860 [size=32]

00:1d.3 0c03: 8086:27cb (rev 01) (prog-if 00 [UHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 17
        I/O ports at 1880 [size=32]

00:1d.7 0c03: 8086:27cc (rev 01) (prog-if 20 [EHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 21
        Memory at d0544000 (32-bit, non-prefetchable) [size=1K]
        Capabilities: <access denied>

00:1e.0 0604: 8086:2448 (rev e1) (prog-if 01 [Subtractive decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=08, subordinate=0c, sec-latency=64
        I/O behind bridge: 00002000-00002fff
        Memory behind bridge: d0000000-d00fffff
        Prefetchable memory behind bridge: 0000000088000000-000000008bffffff
        Capabilities: <access denied>

00:1f.0 0601: 8086:27b9 (rev 01)
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0
        Capabilities: <access denied>

00:1f.1 0101: 8086:27df (rev 01) (prog-if 8a [Master SecP PriP])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 0, IRQ 20
        I/O ports at 01f0 [size=8]
        I/O ports at 03f4 [size=1]
        I/O ports at 0170 [size=8]
        I/O ports at 0374 [size=1]
        I/O ports at 1810 [size=16]

00:1f.2 0106: 8086:27c5 (rev 01) (prog-if 01 [AHCI 1.0])
        Subsystem: 103c:30a5
        Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 20
        I/O ports at 18d0 [size=8]
        I/O ports at 18c4 [size=4]
        I/O ports at 18c8 [size=8]
        I/O ports at 18c0 [size=4]
        I/O ports at 18b0 [size=16]
        Memory at d0544400 (32-bit, non-prefetchable) [size=1K]
        Capabilities: <access denied>

00:1f.3 0c05: 8086:27da (rev 01)
        Subsystem: 103c:30a5
        Flags: medium devsel, IRQ 10
        I/O ports at 18e0 [size=32]

06:00.0 0280: 8086:4222 (rev 02)
        Subsystem: 103c:135b
        Flags: bus master, fast devsel, latency 0, IRQ 18
        Memory at 8c000000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: <access denied>

08:06.0 0607: 104c:8039
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 168, IRQ 18
        Memory at d0004000 (32-bit, non-prefetchable) [size=4K]
        Bus: primary=08, secondary=09, subordinate=0c, sec-latency=176
        Memory window 0: 88000000-8bfff000 (prefetchable)
        Memory window 1: 90000000-93fff000
        I/O window 0: 00002400-000024ff
        I/O window 1: 00002800-000028ff
        16-bit legacy interface ports at 0001

08:06.1 0c00: 104c:803a (prog-if 10 [OHCI])
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 64, IRQ 20
        Memory at d0007000 (32-bit, non-prefetchable) [size=2K]
        Memory at d0000000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>

08:06.2 0180: 104c:803b
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 64, IRQ 22
        Memory at d0005000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: <access denied>

08:06.3 0805: 104c:803c
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 64, IRQ 19
        Memory at d0007800 (32-bit, non-prefetchable) [size=256]
        Capabilities: <access denied>

08:08.0 0200: 8086:1092 (rev 01)
        Subsystem: 103c:30a5
        Flags: bus master, medium devsel, latency 66, IRQ 19
        Memory at d0006000 (32-bit, non-prefetchable) [size=4K]
        I/O ports at 2000 [size=64]
        Capabilities: <access denied>

andersbr@lappy486:~$ asoundconf list
Names of available sound cards:
Intel
andersbr@lappy486:~$ cat /proc/interrupts 
           CPU0       CPU1       
  0:    3075795          0   IO-APIC-edge      timer
  1:      12340          0   IO-APIC-edge      i8042
  8:         37          0   IO-APIC-edge      rtc
  9:     194631          0   IO-APIC-fasteoi   acpi
 12:     108447          0   IO-APIC-edge      i8042
 14:     108162          0   IO-APIC-edge      libata
 15:          0          0   IO-APIC-edge      libata
 17:     623283          0   IO-APIC-fasteoi   uhci_hcd:usb4, i915@pci:0000:00:02.0
 18:    1323582          0   IO-APIC-fasteoi   uhci_hcd:usb3, yenta, ipw3945
 19:       4917          0   IO-APIC-fasteoi   sdhci:slot0, eth0
 20:     347645          0   IO-APIC-fasteoi   ohci1394, ahci, uhci_hcd:usb2
 21:       3609          0   IO-APIC-fasteoi   uhci_hcd:usb1, ehci_hcd:usb5
 22:     121643          0   IO-APIC-fasteoi   tifm_7xx1, HDA Intel
NMI:          0          0 
LOC:    1067465    2664676 
ERR:          2
MIS:          0