I have a problem with my VPN-Client-to-site access when trying to
connect to the server over an existing DialUp-Connection to an
internet service provider.

Connection seems to be successful, as I can see the resolved server
name and the tree name in the VPN-Login-Dialog.
But then, I get an error messeage "Error in user authentification.
vptunnel driver has returned an error."

I have this problem with each username, I tried.
But when my colleague tries the same with one of these users, he
succeeds ?!?

What could be the reason for my problems.
I use VPN-Client 3.7 under Win2000.