Sorry if this is an obvious question, but I'm short of time today and really tired of Google searching. I'm running: Linux dlm-A6200 3.2.0-54-lowlatency #56-Ubuntu SMP PREEMPT Thu Sep 19 17:22:47 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux I have jack 2 connected via ALSA to an M-Audio Fast Track Pro. If there is any slight glitch in the USB power -- for instance, in a performance space where the sound engineer might need to plug/unplug cables frequently -- jackd spins out of control on one CPU and often locks up the user interface, forcing a hard shutdown and reboot. If I'm very lucky, I can get into the terminal, find jack's PID and kill it, but when the mouse and keyboard stop responding, there's nothing I can do reach for the power button. This occurs less frequently in 12.04 than it did when I started with 10.04, but when it does happen (as it did just now), it really, really ticks me off. I think there must be some automated way for the system to recognize that jack is out of control and kill it. [1] notes: -t, --timeout int Set client timeout limit in milliseconds. The default is 500 msec. In realtime mode the client timeout must be smaller than the watchdog timeout (5000 msec). Interesting... "watchdog timeout"... but I have never seen any effect from the watchdog mentioned here. Jack just keeps locking up the system for way longer than 5 seconds. I'm happy to provide more info if you can tell me what commands to run. Normally I would research it myself, but I'm just not in the mood today. If there's already good documentation on this, great, but... too many pages to read and I have no idea which is the best one. Thanks, hjh [1] http://manpages.ubuntu.com/manpages/precise/man1/jackd.1.html