Vista to Vista rdp not working

Basically I have two instances of Vista running in two separate locations.  If I try connecting from Vista to Vista, I will get a black screen and Remote Desktop will just sit there all day until I close it.  If I move my mouse over the window I get the new 'waiting' pointer.  When I attempt to close Remote Desktop, it takes a few minutes for it to close.  Normal RDP sessions close immediately.

At both locations port 3389 is setup to forward to the machines (they are behind firewalls and both are being nat'd).   Network wise, nothing has changed since these were XP machines and RDP worked fine.

I can be on an XP machine in the same subnet as either computer and connect to the remote Vista machine and it will connect fine.  So xp to vista is ok, vista to vista gets black window in Remote Desktop.

I have a similar problem connecting to Server 2003 file shares in our DMZ.  Explorer will hang and the system will run poorly until I reboot.  It seems that something in the WorkStation service gets stuck in a loop..  the service can't be restarted once this starts happening.  I can HTTP or telnet to systems in the DMZ all day, but RDP is super slow (it at least works) and file share access hangs explorer.  I can step over to an XP machine on the same subnet and it can access the shares in the DMZ reliably all day long.

Has anyone else seen these types of problems?  Are there additional ports that need to be opened for Vista to Vista rdp or in the case of file shares, Vista to Server 2003 to work correctly?  Suggestions?

This is the only problem I haven't been able to get fixed in Vista.. everything else has been poor 3rd party drivers.  This is just killing my productivity.