IE5 Not Viewing Intranet

I have gone around and around with this thing. I have one computer which will not access our intranet. We are using Proxy Server and our internet access is done through an ISDN line. She can access the internet fine but cannot access the intranetor any of it’s pages. Everyone else can access the intranet and internet fine. The connections are set the same as all others and there are no restrictions on that one user to prevent intranet access. Any suggestions?