Sometime after I built a computer a couple of years ago with Vista, I started having random loss of audio which would require a reboot. I was never sure if it was caused somehow by iTunes since iTunes always seemed to be running when it would happen. This problem recently cropped up again since I have upgraded to Windows 7. However, I did finally find a solution. What fixes the problem is restarting the Windows Audio service (which also restarts the Creative Audio service). I’m not sure if one or both of these services is the problem, but at least I am able to fix it without a reboot.