When you say "stopped," you could have meant any one of several things, and the difference is important:
- The process is not there anymore.
- The process has frozen in place.
- The process is a zombie... dead, but not buried yet.
I'm going to assume "door number 1."
Most of the time, interesting tidbits can be found in log-files which are typically found in /var/log
, such as messages
. Start by looking there.