There are some thread related bugs in the rc4 release that
Ole Craig ran into last week.
The bugs caused the system to panic because the thread processes
were getting release while still in use by the vproc code.
The panics are NULL pointer dereference panics and the stack
should contain "vpop_report_state" or "vpop_notify_parent".
Thanks to Ole's patience and debugging kernel info, the problems have
been fixed. I have checked in fixes for these problems which will be in the
next release. If you run into these bugs or use threaded apps
you will need to get top-of-tree or apply the attached patch file.