Remote desktop stopped working through firewall

I have a Netgear firewall/router connecting my private
home network to the internet via a single DSL IP address.
The router has been configured to forward port 3389
through to a specific machine inside the private network,
and was working fine until I made some configuration
tweaks to XP on this machine over the weekend.

Now I can make a Remote Desktop connection to the machine
from another machine inside the private network, using
the local private IP, but I can no longer reach the
machine from outside using the public IP the
router/firewall is managing. I confirmed that the router
is not the problem by reconfiguring the forwarded port to
point to a different XP machine that I didn't modify, and
can successfully make a connection from the outside (and
inside) to that one.

Any suggestions as to what might be causing this? IS
there some way to log the connection attempts on port
3389 so I can at least see that the machine is recieving
and rejecting them? I looked and look through MSDN
library docs and searched, but couldn't find anything to
help me enable to sort of logging I need to at least if
the connection request is coming in, and what windows is
doing with it.

Thanks,

Dave