Thank you for the stabs :)
The SystemURL is http://www.safe4all.org
The system is actually on port 8000, but the router is directing it from port 80 to port 8000 inside the LAN.
When I first upgraded, the site actually went down because of this problem. For some reason, the ForceHostP was reset (I believe) to 1, so it would force all requests to go to port 8000. I set it to 0, and it worked.
So I guess my problem might be related to that. The easiest fix might just be to move the port, but this is a really strange error to get, and I have no idea of how to track it down.
Is this a request processor issue?