On a side note, I used to get those all the time, and we were totally baffled as to why; the server wasn't crashing, it looked as if nothing was wrong.
I *finally* tracked it down one night when I was crashing at the house of the guy who ran the server, and I figured I would do some maintenance work while I was there.
The system that the server was on was set to sleep after 15 minutes of inactivity. Nothing at all to do with MC. We felt a little silly.