On the Windows NT 4.0 BDC, check to see if the Netlogon service is started. If NOT, see if the System event log contains:
Event ID: 3210
Description: Failed to authenticate with <ComputerName>, a Windows NT domain controller for domain <DomainName>. Data word: c0000022.
NOTE: The event log on the PDC emulator may not contain an corresponding event, but replication is NOT occurring between the BDC and the PDC emulator.
To adjust this behavior:
1. Control Panel / Administrative Tools / Local Security Policy.
2. Double-click Local Policies.
3. Expand Security Options.
4. Double-click Additional restrictions for anonymous connections and select No access without explicit anonymous permissions.
5. Restart the member computer or domain controller to make the change effective.