VPN Coonection Problems

I Have a remote site that uses a D-Link DI804hv ADSL Router to connect to a
W2K Server using PPTP. The Native support for VPN in XP Pro SP2 attempts to
connect but hangs on Verifying Username and Password. If we re-create the VPN
connection it works until they disconnect, then when they try to reconnect it
hangs at the same point. I have tried numerous things( Router firmware up to
date etc).
The problem seems to reside with the PC as the other 4 users in the same
building don't have any issues. I have changed settings in the VPN
configuration and tried different user accounts on the 2k server but still it
persists. If anyone has any ideas I would be most grateful.