I recently rebuilt my SQL server and now periodically receive the following Track: Sev. 24 Errors:

18456 Login failed for user 'Admin'

The userid does not exist.

My question is: How do I trace the source of this error? In other words, how do I find the origin of this login? I've checked the NT Server security and application logs, but cannot find any further detail. Are there any other logs which might provide more details?

My environment is as follows:

NT 4 Server SP 4
SQL Server 7 Enterprise Edition

Any assistance will be most appreciated!