The sound volume keeps changing itself

Yeah, that's the problem right there. I have tried using both a sound card and the onboard sound, always the same problem. It isn't the speekers since it's the same on another pair of speakers aswell as the ones I use right now.
Can it be a software problem? Most often after It has been on for awhile, regardless of the volume I have put it on, it settles on a setting that is a little to low and if I decide to change the volume again it starts freaking out.

With freaking out I meant that the volume keeps changing from very high to low, back to high, a little lower, very high, no sound.. etc. etc. Then after some time it settles for a random volume level.

OS is XP and the soundcard is a Sound Blaster Live! 24-bit the onboard I don't know what it is but it also does the same thing.