Windows 2000 Server Problem.

I have Windows 2000 Server, with 35 Windows 98 workstation. My proble is as follow:

1.) One workstation automatically disconnects from the server. The coumpter could be the same again or someother computer on the network.

2.) I can ping the Windows 2k server but cannot browse any resources from the server.

3.) I can browse the problem computer on the server.

4.) The problem computer can browse other computers but not the Win2K server.

5.) If I restart the computer it works fine.