Server Crash

I don't really have anything to describe, because I see no pattern to when the server crashes - but it happened multiple times already. Actually, I'm not even sure if it's always the same issue, since the crash reports are very varied, but they seem to happen shortly, one after another, many times in a very short time (even up to 10 crashes in 20 minutes), and then stop for at least a few hours.

I attach several crash reports.