WinXP – The specified server cannot perform the requested operation

I’m getting:

“the specified server cannot perform the requested operation”

When joining a Windows XP Pro Laptop to a Server 2003 SBS box. It’s a reasonably new server; has 2 network cards both configured to resolve DNS name, have turned off Windows Firewall, have scanned for viruses and have checked just about all I can think of on the server.

any idea’s welcome?

Thanks,