Ie-4.0-Navigation Cancelled.-after new proxy-server installed

I have a network with proxy server 2.0, i used to work with 1.0, all information on the new server is the same as the 1.0 server was. Now no IE.(xx) is possible to browse. It is giving me the message Navigation Cancelled. And when fill in my adress anyway it say's: "Internal error occured in windows extensions." What can this be ???? If i install netscape no problem at all.
Any MS crack that can help me, I am desperet
Rene,
IT Manager Planhold.