Upgrading to Windows 2000 AD

Can anyone help?

I have a test server that I created as an NT4 BDC on our current domain, I isolated it onto it's own hub, promoted it to PDC and logged onto it using a NT4 laptop. So far so good. I then upgraded it to Win2K and AD and tried to log in again using the laptop that I had used when the server was NT4 PDC. I got this error message >
Source=Netlogon Cat=none EventID=5722
"The session setup from the computer failed to authenticate. The name of the account referenced in the security database is $. The following error occurred: Access is denied ( note the $ added to the end of the computer name )

Any ideas as MS only point to the machine not being the PDC Operations master which it is!

HELP