ifconfig msk0 up hang and eating 100%CPU

[Andrey Smagin]

"ifconfig msk0 up" hang and I can't kill it, also ping any host via another working interface - ping hang.
What I can do for debug it process ?

FreeBSD 9.0-CURRENT #4: Wed Oct 27 01:00:31 MSD 2010     root@:/usr/obj/usr/src/sys/SAM  amd64

>top
last pid: 58489;  load averages:  6.55,  4.98,  2.76                                                                        up 0+01:53:08  11:37:46
602 processes: 6 running, 594 sleeping, 1 zombie, 1 lock
CPU:  0.2% user,  0.0% nice, 25.6% system,  0.3% interrupt, 73.9% idle
Mem: 354M Active, 200M Inact, 765M Wired, 700K Cache, 76M Buf, 2622M Free
Swap:

  PID USERNAME    THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
57179 root          1 -32    0 14340K  1588K CPU1    1   8:29 100.00% ifconfig