One of our VS .NET 2008 windows forms applications runs from multiple client machines. The application randomly has
login failures from random machines and from random places in the code. The login works almost every time but about once every fifteen minutes an error shows up in SQL Server error logs from a random user. We are running a clustered SQL Server 2005 system
and the database is in 2005 (90) mode.
The following error appears in the SQL Server error logs:
Login failed for 'App_Login'. [CLIENT: XXX.XXX.X.XXX] Error: 18456, Severity: 14, State: 16.
The following error is what the client sees: