mysqld got signal 11

[Ken Chen]

mysql frequently crash with same reason:

070718 10:53:06 - mysqld got signal 11;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help
diagnose
the problem, but since we have already crashed, something is definitely
wrong
and this may fail.

key_buffer_size=268435456
read_buffer_size=4190208
max_used_connections=89
max_connections=130
threads_connected=88
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections =
1326582 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

db1# cat /boot/loader.conf
kern.maxdsiz="2G"
kern.dfldsiz="2G"
kern.maxssiz="134217728" # 128MB
db1# uname -a
FreeBSD db1.xxxx.com 6.2-RELEASE FreeBSD 6.2-RELEASE #1: Wed Jul 11 19:40:25
CST 2007     root at db1.xxxx.com:/usr/src/sys/i386/compile/DB1  i386


What should I do to find the problem? Thank you in advanced!