MSTSC used to work but now????

I have a client computer that I've connected to our servers remotely
with several times. This was done by using Microsoft VPN connection and
then remote desktop. Now, for some reason, while I can VPN into the
network, I cannot connect to the server(s). The real screwy part is
that if I have this computer directly connected to the LAN(via ethernet
cable), i CAN connect to the server(s) remotely. I suspect some
security setting got messed up? some registry key got messed up? When I
installed this God Awful T-mobile EDGE/GPRS/Wi-Fi card (which by the
way is a POS!) I unistalled the card but still can't connect. I
restored the system back to a week before I installed the POS but still
can't connect. Luckily for me it's only the general managers computer!
God only knows what he's done! (did i mention that the reason I've
connected remotely so many times with this machine was to show him how
to do it?) Anyways, I've spent the whole Tigers/Yankees game 4 playoff
game (Next stop-Oakland, look out A's) scanning the net looking for
answers and haven't found it yet so I'm forced to ask somebody wiser
for help. Yes, I'm sure port 3389 is listening. Yes, I'm sure Remote
desktop is enabled in Windows firewall. Remember, i CAN connect
remotely when this machine is connected directly to the LAN. Thanks for
any advice, GO TIGERS! Oh Yeah: XP PRO SP 2 on the client, server 2003
on the server(s). msg is: Client could not connect to remote server,
blah blah balh....