This event could also be caused by a shared printer on a workstation, when the workstation is turned off. When Active Directory tries to verify that the printer is present, it cannot contact the "print server" (the workstation that's off) and raises the error. From what I found, Active Directory performs this check every 8 hours. Solutions would be:
1. If you have configured that workstation as a print server, don't turn it off
2. When you share the printer, uncheck the "List in the directory" box (unverified).
This may be caused by a corrupted printer object on client workstation. Delete and re-add the printer on W2K workstation.
This event may occur on a Windows 2000 domain controller when File Replication Service is unable to update the local schema from the Primary Domain Controller. Look also for event 13508, which will confirm whether this is the issue.