Server instability issues, update

I've run some CPU stress tests for a few hours, but no errors or freezes...

Stopping Samba didn't work, as yesterday evening my server again froze, but at least I didn't see any kernel errors about stuck processes. I've been talking about the COM port stopping, but I have to rephrase that: the UPS software reported it lost communications with the UPS. Maybe just stopping and starting the UPS software could solve that; I'll have to find out when that issue pops up again. Anyway, of course it's still weird, because the UPS software never reported having lost communications before in the last year or so this server is running.

Maybe the SAS controller makes my server hang, by slurping up all I/O or something?

I really have to think about how to proceed further. Until the next update!