Proxy/Exchage not seen by workstation

A couple week ago, a user installed AOL 6.0 on his company Compaq Armada 1700 with windows 95. When he came back to work and logged onto the network. He was successful logging in. However, he could not read or send e-mail thru exchange server 5.5,nor could he access the internet thru proxy server 2.0. I unistalled AOL and reinstalled the proxy server client. Yet, the problem continued.

The OS of the server is Mircrosoft Back Office Small business Server 4.5 (NT 4.0 SP4, exchange server 5.5, and proxy server 2.0). We are using TCP/IP protol.

I would appreciate any and all ideas to fix the problem. Other wise I will use the quick restore CD.