provider denies access

XP-Pro installed on a new machine, single user, no network.
One Asuscom ISDN card, integrated ethernet adapter on the main board.
Drivers for the ISDN card I took from the CD.
Accounts I set up for 2 providers, used the wizzard to make Dialup
connections.
Entered the same user names and passwords as on my previour win98 machine.
Each dialup ends right after 'checking user name and password', so XP
corrupts one or both of them, or doesn't supply them at all.
The ISDN monitor program logs everything that's going in and out up to the
moment the connection is established, so I can't see what's happening.
Is this a common problem? Is there a utility to monitor the dialog with the
ISP?