Log onto the ACS server itself as the local administrator.
Browse to the Bin directory in the ACS program directory.
Run the program there called CSSupport.
Select "Run Wizard" and click Next.
Check all the boxes and create the file for last 3 days and clickNext.
Again click Next.
Select "Set Diagnostic Log Verbosity to Maximum." and click Next.
Click Next, then click Finish.
In an environment where there is more than one global catalog server for the domain, ACS will not search for the secondary" catalog server if the "primary" goes down.
Condition: ACS is installed on a domain member server.
Workaround: Re-start csauth.exe.Let me know if restarting CSAuth makes any difference