When you upgraded your Windows NT 4.0 PDC to an Active Directory Windows 2000 domain controller, your Windows 98 clients can no longer log on. They receive:
This device does not exist on the network.
The domain password you supplied is incorrect or access to your logon server has been denied.
The can happen if the SAM (Security Accounts Manager) has become corrupted during the Active Directory install.
1. Use Addusers.exe to dump the user and group accounts to a text file.
2. Use Dcpromo to remove Active Directory, demoting the domain controller to a server.
3. Use Dcpromo to promote the server to a Active Directory domain controller.
4. Use Addusers.exe to import the users and groups from the text file created in step 1.