Process stuck in STOP state

[Lin Jui-Nan Eric]

Dear listers,

Our FreeBSD Server uses NFS to access PHP files on NetApp, then serve
them with apache 2.2 (worker MPM + php fastcgi mode).
At least one time a day the apache process is stuck in the STOP state
and is unkillable. gdb won't attach to the
process, either. Does anyone have any similar issue?

I have found that may be because of libkse, but we use libthr now.
Thank you all in advance.