I don't know the root of your ills on your server, but I have an interesting story to share (shared by my husband who was an engineer at the company mentioned below).
Back in 1998, the engineers at Be,Inc (who were developing BeOS, a beloved OS at the time) were experiencing kernel panics right after 7 am, on a specific computer. All of the crashes at around the same, while the computer was running tests all night. It had become a big mystery because they couldn't find the bug.
It took them days, but they decided to sit around at 7 am to see what was happening. They saw that a single, strong sun ray was entering the room from the window, and was directly hitting the PC's floppy drive (the PC was not completely closed up with its cover, since it was a test machine). They found that the sun ray would alter some bits in the electronics and what not, and would crash the kernel! :o)