A strange issue surfaced on a client computer which is running XP SP3, hostname is CLIENT1. We have a Windows 2003 domain. The issue is just with this one particular user, his AD account gets locked every few hours automatically. The event 40960 and 40961 are logged in the eventviewer of the client. The DC eventviewer does not show any errors.
The Security System could not establish a secured connection with the server cifs/client2.domain.com. No authentication protocol was available.
The Security System detected an attempted downgrade attack for server cifs/client2.domain.com. The failure code from authentication protocol Kerberos was "The user account has been automatically locked because too many invalid logon attempts or password change attempts have been requested.
Done the following troubleshooting so far.
- Resetting the user password
- Disjoing/Rejoin to Domain.
- Changing the machine SID and computer account name
- Using a static IP address
- Reformatted the PC.
- Checked DNS settings, they are fine
- Checked time synchronization with server
- Changed Kerberos protocol from UPD to TCP.
Any help on how to resolve this issue will be appreciated.