Have you tried following this?

http://support.microsoft.com/kb/299357/

Or maybe this'll help

http://support.microsoft.com/kb/811259/

And I've just discovered a very intersting page that has lots of info on windows networking problem solving.

http://www.michna.com/kb/wxnet.htm

Hope this helps!
_________________________
--Ben
78GB MkIIa, Dead tuner.