Dedicated Server Crashing under Red Hat Linux

I am a running a dedicated server under Red Hat Linux, 3.0GHZ+ Athlon, 2GB RAM, hosted at Rackspace. I am running a slightly altered version of the stronghold demo during testing and have encountered a problem: after 20-30 minutes the game server stops responding to connection requests from my client.

I restart and everything runs fine.

Any recommendations about what server stats to track while troubleshooting this problem. Or what might be causing the crash?

The game downloads perfectly to my client and plays fine.