Vista - RDP not working for outside network

I previously had this working, and I dont know what I did to break it.

I am running Windows Vista behind a router. I have been using a nonstandard
port via registry change for years (upgrade from XP). That port is forwarded
in my firewall and if I telnet to my external IP using this port, it connects.

However, when I connect using RDP client to my external IP and port, it
tells me my credentials did not work. (I am using COmputerName\UserName])

But, if I connect using my local IP and that same port, it will connect
using RDP and tell me, as expected, that the console is in use and I cannot
create another console connection.

Whats strange, when I connect using the external address, it will show the
correct logon icon graphic next to my name. If I enter another user account,
it will show that logon icon graphic as well.

I am guessing that its able to connect using my external address, but for
some reason authentication isnt being passed either in or out of the vista
firewall. I have checked the logs, whcih are logging success and denied, and
I only see success.