Domain Controller and Active Directory confusion

[pasound]

Just joined the I.T. staff at work as the assistant. Finished a new XP Pro box for a worker at one of our remote sites - named it, joined our domain, set up Outlook joined to our Exchange Server, and the Symantec Corp AV - logged in as the user, his mail worked, and all seemed ok.

I.T. Lady leaves on her vacation...

User calls in and says he can't log in anymore. (He's 150 miles away - we have Fortinet "controllers" to set up VPN's into our system.) We hassle with it, I see he's running a very old rig with 2000 Pro, new machine is XP Pro, and both have the same name... not good - and I.T. Lady told me to "name it XYZ"...

I change the name of the XP box to "XYZ2", rejoin it to the domain, and XYZ disappears from the Active Directory. He still can't log in.

Now, the Domain Controller is running 2000 Enterprise. I add the machine back into Active Directory by hand - still no go...

The machine 150 miles away is going to have to have it's name changed and rejoin the domain, I'm thinking... GRRR - means I have to "violate the prime directive" and give him the "god password" to get the name changed, or it's a road trip I don't have time to make - XP and 2K3 Server don't muck around with this stuff... they just "seem to do it".

How's my reasoning here, IT gurus? Or am I off base and need a shortcut not in the manuals?