Message "domain not available" when trying to connect via VPN

[trekker325]

We have a user who works from a remote location and has to connect to
the server via VPN.
Last Thursday, he tried to connect his laptop to his home network by
removing it from the domain and changing to WORKGROUP.
As a result, he can no longer access the domain.
Since then, we have been able to add the laptop back to the domain but
when the user tries to log on,
he receives the message:

"The system cannot log you on now because the domain <domainname> is
not available"

The user CAN log onto the laptop as a local Administrator and then
connect via VPN to the network.
But he cannot log onto the laptop with his domain account.
Also, we tried having him connect with his domain account AND
by checking off the option to log on via the "Log on using dial-up
connection" option but the same message appears.

The OS on the user's laptop is Windows XP Prop with Service Pack 2.

Any suggestions?

 

[Gary]

Did you add the laptop to the domain from the laptop?

 

[trekker325]

Problem resolved! We had tried removing/adding the laptop from the
domain (thanks for the suggestion, Gary) but the problem remained. We
then decided to remove the laptop from the domain, rename it by adding
an "a" at the end of the name, and adding it back to the domain with
the new name. We were then able to log on using the "Log on using
dial-up connection" option at the log-on screen and were successful in
authenticating to the domain.