Event ID 680 LCS 2005

Jamie McKillop
Jamie McKillop used Ask the Experts™
I'm running LCS 2005 on Windwow 2003 SP2. I have a user that is unable to logon. In my Security log, I'm seeing Event ID 680.

 Logon account:      xxxxxxxxx
 Source Workstation:      xxxxxxxxx
 Error Code:      0xC0000064

The client receives the error "Cannot sign in to Communications Service. You may have entered your sign-in name, username, or password incorrectly, or the authentication service may be incompatible with this version of the program..."

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Are you able to sign on to Communicator with another user id on the problem user's machine?  Is the problem user able to signon to Communicator from another machine?
Reason I ask is to rule out whether problem is with user's machine or their account.
Check whether there has been any OS hardening applied on the LCS servers.Run GPEDIT.MSC on LCS server and navigate to Computer configuration/Windows Settings/Security Settings/Local Policies/User Rights - Access this computer from the network and verify that Everyone, Administrators, Users, and Backup Operators are listed.
While in GPEDIT navigate down to Local Policies/Security Options - Network Security: LAN Manager authentication Level.  Check this on Domain Controller, LCS Server and Workstation.  If there's a mismatch it can cause NTLM authentication failure.
I was able to figure this out. Turns out the user was entering his sign-in name when prompted for his username. This despite me walking him thorugh it over the phone three previous times.


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