If I can just hijack this thread for a minute
I have a very similar problem and a similar set up. I have a laptop running Win Server 2003 which is connecting to a cable modem/router. When I installed Server 2003 i check the Internet Connection and it was working fine (I added Google to trusted zone and it connected just fine, picked up an IP address etc). All good.
Then I installed AD, DNS and File Server and restarted.
Now I cannot connect to the Internet from the Server - I get no IP address at all. I cannot ping my router (192.168.0.1) where as another machine I have connected (running XP) can see it, ping it etc fine.
I presume it is something to do with the roles I have added but am a bit lost. The previous poster found removing Network Load Balancing worked - I don't have this installed to start!
An ipconfig /all readout gives me thus:
ip add = 0.0.0.0
subnet mask = 0.0.0.0
dhcp enabled = yes
DHCP server = 255.255.255.255 (Should be 192.168.0.1 (my router) surely?)
Any help/ideas/abuse greatly appreciated