Vista hangs at welcome screen (or changing password screen) forever

Vista is logging onto a SBS 2k3 domain. When it comes time to change
the password the password is changed however Vista hangs at either the
'changing password' screen, or the 'welcome' screen forever, i have
waited 30 minutes with no results. I know the password has changed
cause I can logon elsewhere. If I power off and reboot I will not be
able to logon unless I use a different user like Administrator. The
only solution I have found is unplug the nic, power up, logon (with
new password (and it works)), then plug in the nic and reboot.

I don't see any glaring errors in any eventlog.

This happens every 90 days, to every vista user.

This happens on 3 different vista workstations.