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Event IDs 40960 + 40961

Posted on 2011-02-21
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Last Modified: 2012-05-11
Hello Experts,

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.

___________________________________________________________________________

40960
The Security System could not establish a secured connection with the server cifs/client2.domain.com.  No authentication protocol was available.

40961
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.

Regards,
Abby
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Question by:Abbas9889
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Expert Comment

by:Lukasz Chmielewski
ID: 34941107
There are several other suggestions available on the eventid.net, did you check them ?
http://www.eventid.net/display.asp?eventid=40960&eventno=8508&source=LSASRV&phase=1
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Expert Comment

by:danny1875
ID: 34942745
Hi Abby,

How many DC's do you have in your organisation?
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Author Comment

by:Abbas9889
ID: 34951148
Hi Guys,

I have checked the solutions given the eventid.net link above.  Now, i have changed the NIC card on the PC and also changed profile, then gave the user another PC.

The issue seems to be AD account related.  We have a total of 5 domain controllers, 3 in our main site and 2 in DR site.  This PC is in the main site.

We have around 225 PCs here and only this seems to be giving this strange issue.

Any AD-related suggestions please.

Abby.

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Accepted Solution

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danny1875 earned 500 total points
ID: 34952137
Could it be possible that there is an application or service on your network that uses the users account details to run or start a service? If their password has been changed and the service or software credentials are still the same, or cached somewhere, AD will lock the account due to the failed logon attempts.

If the user is desperate for this to stop happening, you could always up the lockout limit while you attempt to fix.

Hope this helps
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