hi,

I'm using MS Access application that connects with SQL server 2008 r2 Express through ODBC with trusted connection (windows Authentication) .

The Weird thing is, that the user's get the connection and are working perfectly O.K, But SQL Log File shows Infinite number of failed connections With error 18456 State 5.

Needless to say, these Errors are displayed at the Event Viewer Causing my system's Handlers to think that there is something wrong with the users connections to the SQL server db's...

At then mean time I've set my "Login auditing" to "None" and restarted the SQL service for the changes to take effect, and now all is good, But "under the surface" the error still exits so i'd like to understand:

1. why this error occurs ?!?!?

2. How Can I Fix It ?

3. for general Knowledge: How is it possible to get a connection Error While the user is connected properly ?

thanx

State 5: "Could not find a login matching the name provided." So something somewhere is trying to log in with a non-existing login. Furthermore, Aaron Bertrand says on http://sqlblog.com/blogs/aaron_bertrand/archive/2011/01/14/sql-server-v-next-denali-additional-states-for-error-18456.aspx
Like state 2, the login does not exist in SQL Server, but the login attempt came from the local machine. 

So you need to check the SQL Server machine for processes that try to log on to SQL Server.