Comment 14 for bug 158590

I started having this in my fresh install of Hardy. I do not have USB sound. I have a PCI Razer Barracuda (CMedia CMI8788), attached to surround speakers. For me the erratic volume control behavior was only associated with the "Master" channel, and happened whether I used keyboard volume keys or mouse to adjust. I got around this problem by setting the master channel to full and hiding it in volume control, so only PCM showed. I then right-clicked on the Notification Area volume applet -> preferences and switched to PCM. I then went to System -> Preferences -> Sound and chose PCM at the bottom as the track controlled by keyboard.

Fixed it for me.