Inbound connections fail, outbound connections are fine - firewall shut off, very strange

This is a strange one. I have a XP Pro machine in a domain. It's
working fine up to a point. It can access file shares on a server, it
can access a mailbox on the Exchange Server via Outlook. The internet
works fine, it can access other computers in the domain...everything
looks fine.

The trouble comes when I try to connect to it from the server or
another computer in the domain. I get the "network path not found"
error message. I can't even ping the computer. It shows up in the
domain list but can't be connect to. The Windows firewall is turned
off and no other firewall is installed...

This is really strange, any thoughts or ideas? I thought maybe the
cause was an upgrade from XP home I did but I did a complete
reinstall..but that didn't help.

Thanks!