Bleah, ever since the jobs site went up, the server has been a bit unstable under mid-day high traffic. I've scoured the error logs and patched tons of little problems, and each time the server seems a little more stable but continues to periodically die.
It appears there are a lot of little bot attacks, where someone is making the same malformed request hundreds of times in a row. About all I can do now is make sure the malformed requests don't do anything aside from send a short error and keep server processing to a minimum. Hopefully things start looking up soon, as I'm spending the rest of today further shoring up the server from these sorts of problems.