W2K dialup problems, hacked?

I have a small test network, with one Windows2000 server. As this is a test network, I have only 56k dial up, and I dial in mostly from the server. As of today, If I connect via dial up, I can not disconnect at all. The only way is to re-boot the server. In trying to trouble shoot, I went to look at Services, and I could not right click to look at services properties either.

Although the test workstations have stuff like zone alarm, I had no firewall protection on the server, has the system been hacked? How do I tell, and how would I fix this?

Also, I wanted to run zonealarm on this server, but had trouble getting it to work with zonealarm on the workstations.

Any help at all would be much appreciated!!
Thanks