Another sound-related minor bug with new iBooks?

"If the iBook goes more than exactly 30 seconds without making a sound (e.g., an alert beep, a music file, an event sound, etc.), the next time a sound occurs (e.g., an email alert), it is either completely muted or drastically muffled. Once the system has attempted to play this sound, the audio will work normally again (until 30 more seconds of audio inactivity have passed).

The easiest way to replicate this is to just hit the volume up button on the keyboard until the volume level reaches the top... then wait 35 seconds... then hit it again... you will hear either nothing or a very muffled beep.

It turns out the problem is caused by using the SoundSets feature in the Appearance Control Panel. Turn on a SoundSet (even Apple's stock platinum one) and the problem appears. Turn SoundSets off, and the problem is gone. I don't know if this applies to all iBook machines or just iBook with CD-RW/DVD drives, but I have seen several other reports of this from users with CD-RW/DVD iBooks."