After going to sleep, Wallstreet looses sound?

Laurent Daudelin wrote on :

Twice while running off the battery yesterday, my Wallstreet would loose the sound. Going to the sound control panel, playing with any setting there wouldn't produce anything except when I restarted.

However, I would get sound when playing a DVD, though. Anything else, even clicking outside an alert on screen wouldn't play the system beep. If the Wallstreet goes to sleep on AC Or is booted in OS X, the sound still works when the laptop is waken up.

Any idea about what can cause this? I'm currently running 9.2.1 with 256 MB RAM. Actually, I've been running 9.1 up until a couple of weeks ago and although I don't use the Wallstreet off the battery very often, I don't remember seeing something like this all the time that I've been running 9.1. Any relation?