Connectivity to the remote computer could not be established using remote desktop through SBS server

If you have an sbs 2003 server and are using remote desktop, when you attempt to connect to one of the computers on the network you may receive the following message:

Connectivity to the remote computer could not be established

The typical cause of this is if you have a hardware firewall you need to port forward 4125 on TCP to the servers IP address.

See http://forums.techarena.in/small-business-server/385504.htm

for further info.