Workstation can't see all servers

I have an XP sp1 computer that cannot see all of my servers. I have 3
other computers (2 win2k and 1 server 2003) on the same network and they
can see all servers. The gateway and dns servers are the same for all
computers. I have no idea why the XP computer can't see all servers.
(If I do Start|Run and type in //servername I get the following error:
No network provider accepted the given network path. I can ping the
servers IP address (this server has multiple nics and I did only try 1
ip address).

I can type in //servname2 and it will work fine.

any ideas?

Thanks