I recently did a fresh UbuntuStudio 10.4 amd64 install.  I found that I could only

start qjackctl once without rebooting. When I attempted to close jackd with the

Quit button on qjackctl, the next attempt to run it results in the following message:

JACK compiled with System V SHM support.

loading driver ..

Enhanced3DNow! detected

SSE2 detected

apparent rate = 48000

creating alsa driver ... hw:0|hw:0|256|2|48000|0|0|nomon|swmeter|-|32bit

control device hw:0

23:08:49.544 JACK was stopped successfully.

23:08:49.544 Post-shutdown script...

23:08:49.545 killall jackd

23:08:49.549 JACK has crashed.

jackd: no process found

23:08:49.993 Post-shutdown script terminated with exit status=256.

23:08:50.025 Could not connect to JACK server as client. - Overall operation failed. -

Unable to connect to server. Please check the messages window for more info.

Neither "sudo kill -9 <PIDs of jackd, qjackctl and qjackctl.bin>" nor "sudo pkill -9 qjackctl" 

nor closing the terminal in which qjackctl was executed eliminates this problem.

Since this was a clean install with very little added beyond ambdec, tetraproc and mhwaveedit,

I don't have any explanation for this problem except bad karma between the current UbuntuStudio

and qjackctl. On one occasion when starting the reboot, I got an error message asking if I  

wanted to wait for process Unknown to complete. 

The good side to this is that UbuntuStudio 10.4 boots up quickly.

Does anyone have any ideas?

Thanks,

John