I'm having a different volume problem that is driving me nuts. I'm about to uninstall everything and start from scratch, and reload XP too if necessary.
Basically, any audio transition (song ends and change to next song, pick an internet radio station, etc.) causes the audio to drop out. Usually I can then go into the Mixer screen and touch the WAV slider (which is at 100% BTW) and just changing it a bit will fix things. But I have had to go to the Windows advanced audio controls more than once to restore sound. Sometimes both the Bass and Treble sliders will drop all the way to zero. Today the BAL got set to Left only.
Something is clearly not being set up and changed properly with regard to audio. I'm using WinAmp (current as of a month ago) with the linein plugin, could that be the culprit? I'd gladly change to WMP or Foobar if they are preferred now.