Screaming iBook

[Lawrence Anderson]

I've had a problem develop that has me puzzled.  I'm running YDL 2.3 on an 
iBook (dual-USB, 2001 model, 600MHz/384MB).  On occasion, when I wake it up 
from sleep (which it seems to do nicely), something goes wonky with the sound 
and it emits a piercing shriek from the speakers, regardless of what the sound 
level is set at (I normally keep the volume turned down to 0 and then mute it 
for good measure). When this happens, the only way to stop it is by turning the 
computer off.    Anyone have an idea what's causing it, or how I can stop it 
from happening?  I'd really rather use YDL, but right now I'm booting into OS 
X, because I use the thing in a classroom setting and can't have it suddenly 
screaming at me.  Help!