I want to use PulseAudio on top of jack, so I've turned pulse off and now want to start jack using qjackctl. However, this results in the following error log:

22:14:15.933 Patch Panel disabled

22:14:15.940 Reset statistics.

22:14:15.953 Changed ASLA connection.

22:14:15.970 D-BUS: Service available (org.jackaudio.service aka jackdbus).

Cannot connect to server socket err = File or directory not found

Cannot connect to server socket

jack server is not running or cannot be started

22:14:15.980 Updated visualization of ASLA connections

22:14:18.147 D-BUS: Unable to start JACK server

Cannot connect to server socket err = File or directory not found

Cannot connect to server socket

jack server is not running or cannot be started

Fri Jul 20 22:14:18 2012: Starting jack server...

Fri Jul 20 22:14:18 2012: JACK server starting in realtime mode with priority 10

Fri Jul 20 22:14:18 2012: [1m[31mERROR: Cannot lock down 82246176 byte memory area (Cannot allocate memory)[0m

Fri Jul 20 22:14:18 2012: control device hw:0

Fri Jul 20 22:14:18 2012: control device hw:0

Fri Jul 20 22:14:18 2012: [1m[31mERROR: Failed to acquire device name : Audio0 error : Cannot allocate memory[0m

Fri Jul 20 22:14:18 2012: [1m[31mERROR: Audio device hw:0 cannot be acquired...[0m

Fri Jul 20 22:14:18 2012: [1m[31mERROR: Cannot initialize driver[0m

Fri Jul 20 22:14:18 2012: [1m[31mERROR: JackServer::Open() failed with -1[0m

Fri Jul 20 22:14:18 2012: [1m[31mERROR: Failed to open server[0m

Fri Jul 20 22:14:19 2012: Saving settings to "/home/jan/.config/jack/conf.xml" ...

22:14:24.418 Cannot connect to JACK server as client - connection failed. See message dialog for details.

Cannot connect to server socket err = File or directory not found

Cannot connect to server socket

jack server is not running or cannot be started

(Several messages were in German, I did my best translating them)

The pulseaudio process is defenitely not running.

I use Ubuntu 12.04 64 bit with an NVIDIA audio card.