Win 2k3 Server loosing default Gateway

Hello everyone,
I have a Win2k3 Web Edition server that is hosting Web and FTP site. I
recently installed SP2 and lately it has intermittingly been dropping
connections from outside networks. That is to say, from in the office here
I don't see a problem but if someone not in the office tries to connect it
won't. When this behavior starts I can't even ping the server with
http://www.fifi.org/services/ping.
I had this problem once before on the same server with the same hardware
and everything after I installed SP2. At the time I couldn't figure it out
and SP2 wasn't all the necessary so I just uninstalled SP2 and haven't had a
problem since. This time I need SP2 so uninstalling it isn't an option.
One thing I have noticed that I didn't before now is that during this
behavior the Default Gateway is missing from ipconfig /all. A simple change
to the interface, like changing the metric from auto to 1 brings everything
back up for a bit but it all eventually happens again.
has anyone seen this behavior before and/or found a solution to it?

Thanks,
--
-Scott