This is really annoying, and I can't figure out what's doing it. Is it iTunes 4? After a few hours of using my beautiful new 17-inch PowerBook, the sound balance of my speakers shifts to the left or to the right. This isn't just perceived; I can open up the Sound Preference Pane and see exactly how much they've shifted. This has happened several times now. I am certain that a user isn't doing this; I'm the only one and I know better. What else could cause this? I hate having to open up that Preference Pane all the time to get normal sound!