can't start jackd

Cannot connect to server socket err = No such file or directory
Cannot connect to server socket
jack server is not running or cannot be started
17:41:37.167 ALSA connection change.
17:41:55.104 Startup script...
17:41:55.105 artsshell -q terminate
Cannot connect to server socket err = No such file or directory
Cannot connect to server socket
jack server is not running or cannot be started
17:41:55.516 Startup script terminated with exit status=256.
17:41:55.516 JACK is starting...
17:41:55.517 /usr/bin/jackd -dalsa -dhw:0 -r44100 -p1024 -n2
17:41:55.522 JACK was started with PID=22044.
Cannot create thread 1 Operation not permitted
Cannot create thread 1 Operation not permitted
jackdmp 1.9.6
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2010 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
Cannot lock down memory area (Cannot allocate memory)
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|hw:0|1024|2|44100|0|0|nomon|swmeter|-|32bit
Using ALSA driver HDA-Intel running on card 0 - HDA ATI SB at 0xf9ff4000 irq 16
the playback device "hw:0" is already in use. Please stop the application using it and run JACK again
Cannot initialize driver
JackServer::Open() failed with -1
Failed to start server
17:41:55.595 JACK was stopped with exit status=255.
17:41:55.595 Post-shutdown script...
17:41:55.596 killall jackd
jackd: no process found
17:41:56.001 Post-shutdown script terminated with exit status=256.
17:41:57.539 Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.
Cannot connect to server socket err = No such file or directory
Cannot connect to server socket
jack server is not running or cannot be started