I run the perl script in screen (I can log in and check debug output). Nothing in the logic of the script should be capable of killing it quite this dead.

I'm one of only two people with access to the server, and the other guy swears that it isn't him (and we both have quite a bit of money riding on it continuing to run without a hitch). I have no reason to believe that some hacker has managed to get a shell or anything like that. I have very little reason to suspect the admins of the host operation (bandwidth/cpu-wise, this script is pretty lightweight).

Screen continues to run, but at the end of the output of the perl script I see "Killed" and it has dropped back to a prompt. How do I go about testing what is whacking the damn thing?

I've checked crontab, nothing in there that would kill random/non-random processes. Nothing in any of the log files gives any hint. It will run from 2 to 8 hours, it would seem (and on my mac at home, it will run well over 24 hours without a problem). The server is running Ubuntu version something or other, I can look that up if it matters.