FS 2004 Multiplayer Connect Problem

I am trying to help a friend host a FS 2004 Multiplayer session on a Vista standalone computer. He can connect to a session I host but no one can connect to his multiplayer. Here is what we have unsuccessfully tried so far in the order listed:

Verified his IP address using www.whatsmyip.com
Used the default multiplayer host and client ports
Disabled his Windows Firewall
Disabled his anti-virus and spyware programs
Entered FS 9 to his firewall exceptions list
Disabled all startup up items with msconfig
Manually removed the FS 9 folder ... the windows uninstall featue
would not function ... but did not edit the registry due to his concerns.

In each instance I was unable to find his hosted multiplayer session. Any
suggestions would be greatly appreciated.

I had the same problem.
I have Window XP and my friend have Vista.
He can connect to the multiplayer game if I host the session. But I cannot connect to his session if he host the session.

Rocky