Same thing for me. 

crashes 3 out of 5 times

-=-=
23:49:44.627 D-BUS: JACK-Server konnte nicht angehalten werden. Tut mir leid
Fri Dec 21 23:49:44 2012: Client 'qjackctl' with PID 25031 is out
Fri Dec 21 23:49:44 2012: Stopping jack server...
Fri Dec 21 23:49:44 2012: Client 'system' with PID 0 is out
Fri Dec 21 23:49:44 2012: ERROR: Abort!
Fri Dec 21 23:49:44 2012: ERROR: info.si_signo = 6
Fri Dec 21 23:49:44 2012: ERROR: info.si_errno = 0
Fri Dec 21 23:49:44 2012: ERROR: Segmentation Fault!
Fri Dec 21 23:49:44 2012: ERROR: info.si_signo = 11
Fri Dec 21 23:49:44 2012: ERROR: info.si_errno = 0
Fri Dec 21 23:49:44 2012: ERROR: info.si_code  = 1 (SEGV_MAPERR)
Fri Dec 21 23:49:44 2012: ERROR: info.si_addr  = 0x525245
Fri Dec 21 23:49:44 2012: ERROR: reg[00]       = 0x00007fb07a1292b8
Fri Dec 21 23:49:44 2012: ERROR: reg[01]       = 0x0000000000000000
Fri Dec 21 23:49:44 2012: ERROR: reg[02]       = 0x00000000ffff8000
Fri Dec 21 23:49:44 2012: ERROR: reg[03]       = 0x0000000000000246
Fri Dec 21 23:49:44 2012: ERROR: reg[04]       = 0x00007fb07a1296f8
Fri Dec 21 23:49:44 2012: ERROR: reg[05]       = 0x0000000000413c3b
Fri Dec 21 23:49:44 2012: ERROR: reg[06]       = 0x0000000000000014
Fri Dec 21 23:49:44 2012: ERROR: reg[07]       = 0x0000000000000000
Fri Dec 21 23:49:44 2012: ERROR: reg[08]       = 0x0000000000525245
Fri Dec 21 23:49:44 2012: ERROR: reg[09]       = 0x0000000000413c4d
Fri Dec 21 23:49:44 2012: ERROR: reg[10]       = 0x00007fb07a1293f0
Fri Dec 21 23:49:44 2012: ERROR: reg[11]       = 0x00007fb07a129400
Fri Dec 21 23:49:44 2012: ERROR: reg[12]       = 0x0000000000000018
Fri Dec 21 23:49:44 2012: ERROR: reg[13]       = 0x0000000000000000
Fri Dec 21 23:49:44 2012: ERROR: reg[14]       = 0xffffffffffffffff
Fri Dec 21 23:49:44 2012: ERROR: reg[15]       = 0x00007fb07a128d90
Fri Dec 21 23:49:44 2012: ERROR: reg[16]       = 0x00007fb078eb83b1
Fri Dec 21 23:49:44 2012: ERROR: reg[17]       = 0x0000000000010246
Fri Dec 21 23:49:44 2012: ERROR: reg[18]       = 0x0000000000000033
Fri Dec 21 23:49:44 2012: ERROR: reg[19]       = 0x0000000000000004
Fri Dec 21 23:49:44 2012: ERROR: reg[20]       = 0x000000000000000e
Fri Dec 21 23:49:44 2012: ERROR: reg[21]       = 0x0000000080005a27
Fri Dec 21 23:49:44 2012: ERROR: reg[22]       = 0x0000000000525245
Fri Dec 21 23:49:44 2012: ERROR: Stack trace:
Fri Dec 21 23:49:44 2012: ERROR:  1: 0x7fb078eb83b1 <_IO_vfprintf+10737> (/lib/x86_64-linux-gnu/libc.so.6)
Fri Dec 21 23:49:44 2012: ERROR:  2: 0x7fb078f75d80 <__vsnprintf_chk+176> (/lib/x86_64-linux-gnu/libc.so.6)
Fri Dec 21 23:49:44 2012: ERROR: End of stack trace

-=-=-

$ jackd --version
jackdmp 1.9.8
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2011 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
jackdmp version 1.9.8 tmpdir /dev/shm protocol 8

$ uname -a
Linux htpc 3.2.0-35-generic #55-Ubuntu SMP Wed Dec 5 17:42:16 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

$ lspci |grep "Audio"
00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04)
01:00.1 Audio device: NVIDIA Corporation GF110 High Definition Audio Controller (rev a1)