Mac OS X Server loses connectivity w/o constant ping

I have a user that is running a server (Mac OS X on a G4) in the DMZ of my network. He had rendezvous turned on and we noticed that the DMZ was getting UDP broadcasts from his box; since he wasn't using it and it was affecting the whole segment, I asked him to turn off Rendezvous. Since this has happened, if he doesn't run a constant ping, his server loses connectivity. The box does not appear to have any hardware failure and is fully patched w/ the latest os x server. What could be causing this? I'm stumped; I've also posted this over at experts-exchange.com (here) if anyone here's a member there and wants to earn a quick 500 points.