Conflicting credentials

Windows NT 4.0, SP6a server with NT workstations.
Running MS TCP/IP with DHCP. IP addresses are
being assigned correctly.
Upgraded an existing NT 4.0 w/s to Win2000 and now
when attempting to create an account in the domain,
using "Administrator" and the correct password, we get
the message:
"The credentials supplied conflict with an existing
set of credentials. "
All other NT workstations are still logging into the
domain with no problem.
Changed the computer name, reinstalled SP6a on the
server. Can Ping the server, map a drive to the server
but just can't join the domain.
Brought the computer to our office and joined our domain
(same version of NT on our server) without any problem.
It appears the problem is with the NT server configuration
on-site. ??????????????????????????????????

 

try clearing the computer account from the domain and any references to it in DNS and WINS