My volume control applet and the "Sound Preferences" / "Output Volume" doesn't work (it doesn't affect the volume).
alsamixer on the other hand works.
Any ideas of what could cause this? (Running natty with Gnome 2.32)
I have seen this type of behaviour when you aren't adjusting the output volume on the active audio output device. In my case when I connected a USB audio device audio output would switch to it, however the volume control would control the unused onboard audio.
If you open the sound settings window do you see more than one output device? Does the volume control on one of the output devices work correctly?
Here's some (solutionless) discussion of the same issue: https://answers.launchpad.net/ubuntu/+source/gnome-media/+question/5735