When you try to install a Windows NT 4.0 BDC into a domain with a Windows 2000 PDC, you receive:
The Machine Account for This Computer either does not exist or is inaccessible.
If you try to add the computer account using the Windows NT 4.0 Srvmgr program, you receive:
The Network Request is not supported.
Your Window 2000 PDC may have the following event:
Source: SAM EVENT ID: 12298 DESCRIPTION:The Account "COMPUTER$" Cannot be converted to be a domain controller account as its object class attribute in the directory is not a computer or is not derived from computer. If this is caused by an attempt to install a pre Windows 2000 Domain, then you should recreate the account for the domain controller with the correct object class.The problem exists because Windows NT computer accounts are really user class objects.
To add a Windows NT 4.0 BDC, use Svrmgr from Windows 2000, on a Windows 2000 computer, to pre-create the computer account for the Windows NT 4.0 BDC.
See Tip 2887 - How can I create a Computer object in Active Directory for a Windows NT 4.0 BDC?
You can use ADSI Edit to modify the userAccountControl property.
If the Window NT 4.0 BDC is already installed, use NLTest to reset the secure channel.