Comment 1 for bug 134639

I'm having a similar problem with my HP nx7300 and the laptop mute button. I've also upgraded from Feisty to Gutsy, although I'm using Kubuntu.

When starting gutsy, the laptop mute button/light pings on during the boot process, muting the sound. Pressing it later on does not unmute/turn the light off but the event is being registered somewhere as I get the "mute on/off" OSD. Volume up/down also work fine although, since sound it stuck on muted, I can't tell if they're actually changing the sound output. Pressing the mute button does not generate entries in /var/log/acpid (although I'm not sure it's supposed to).

The odd thing is, if I boot into Gutsy with my old Feisty kernel (2.6.20-16-generic), the buttons work as usual, so I'm using that for now.

Hardware is almost the same as OP:
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 01)

On the lighter side of things, all of the other function buttons seem to work and the "bad state" problem these laptops were famed for seems solved with gutsy...!