strange hung processes

We're running 7.4.9 and have run into something strange.

A group of processes seem to have hung and cannot be killed.  netstat
showed that there were no active TCP connections at the time.  Sending
SIGTERM to the parent process caused PG to begin its shutdown, but it
never finished.  We then kill -9 the postmaster, which caused it to die,
but these child procs remain, even after a clean restart.  Our next step
is to reboot the box, but before we do, I'm just curious anyone else has
seen this,  why this happened, and if anyone know ways to prevent this
from happening again.....

thanks

--
jeremy ashcraft
operations/development
EDucation GATEways
jashcraft@edgate.com