Many people have had problems with DR2.1 update 6 freezing after it beeps a few 
times.  This is a known bug and will be fixed in Update 7 or DR 3.0 (i assume).    
Because of the new sound support, a bug was added accidentally.   In the 
meantime, Gary has fixed the bug in a WIP (work in progress) kernel:


>  I've made a WIP kernel which should fix the "my system dies after making
>  the 'whoop' sound" , etc. problems many of you have had with Update #6.
>
>  Please give this kernel a try:
>   ftp://ftp.mklinux.apple.com/pub/wip/971117/Mach_Kernel

Just another note.  If you don't want to install the work in progress kernel,
you can avoid the beep all together by typing:

xset b off

This will turn off beeping under X (as long as you use X).  No Whoop = No Crash.

-Jeff Alexander
jalex@x23.com