jack and sound restarting

[john]

Hi everyone,
I think I already brought this up before (thanks for your patience), but
found no real solution to the problem: 

whenever jack freezes or stops running unexpectedly, after killing it or
restarting it, it WONT work any more. I have been forced to restart the
PC every time and as you might guess, it is a real problem!
 
So my question is: how can I completely kill and restart the whole sound
system without restarting the matchine? I've tried killing jack through
the terminal and the device manager. That doesn't do the trick! My guess
is I need something that problably restarts ALSA altogether.
Any ideas??

Many thanks!

John