[ActiveDir] XP SP2 and AD

[Za Vue]

I got a Dell laptop running XP SP2 that cannot join Active Directory. The option to join the domain is grey out. Yes, I am logged in as an administrator. I can ping and even remote desktop into the PDCs. Other machines in the office have no problem join the domain.   I have added the domain to the "Append these DNS suffixes" tab and the firewall is disabled.   Suggestions??   Thank you Z.V.