I had a ghost in my laptop. Amongst other things, screwing around with the volume was his highlight of the day. At first I thought it was my girlfriend, or a friend using my computer and turning down the volume in the sound control. Then I started noticing that the volume would go down when nobody else had used my computer.
And at first, it always took me a while to figure out the main volume had been lowered. I kept thinking these speakers suck, I need to get some decent speakers for this thing.
God knows what the hell was going on. Me and that laptop parted company when it had an unfortunate accident with a wall.