Server 2000 can’t talk outside local net

I administer a Windows 2000 server with about 15 users. The server cannot communicate outside the local network (no Internet access). I have verified the default gateway and DNS settings. I have also changed these and changed them back with no effect. The client workstations have the same settings and can access the Internet without any problem. From the server I can ping local machines, the default gateway and the T1 “router” on the public side of the gateway, but nothing else. Cannot ping the DNS servers. The server used to be able access the Internet. It may have lost access when I installed Terminal Server, but I’m not sure. Any ideas? I need to get this working and I’m running out of ideas.

Thanks,
Jon