AD Account lockout

I have a user that is getting repeatedly locked out of his Active Directory account.  I have checked his mobile phone and removed and re-added the exchange account with the correct credentials.  I have run rundll32.exe keymgr.dll, KRShowKeyMgr --  and removed all cached credentials.  I have deleted the cached passwords from Internet Explorer.  I have checked for any mapped drives and I have removed and re-added the Outlook profile.  

I h ave also downloaded and ran the lockoutexaminer.  This shows the orig. lock as one of our domain controllers.  

I have checked the security event log on the DC for event  4740 and it shows the lockout and the caller computer name is our Exchange server.

The lockouts started happening after the last password change.  I also tried changing the password back to the original password,but that did not help either

The lockout appears to occur at regular 15 minute intervals.  

Is there anything else I can check to find the source of the account lockout?

Donna HSr. Manager of ITAsked:
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Shaun VermaakTechnical SpecialistCommented:
Jeff GloverSr. Systems AdministratorCommented:
Perhaps searching the IIS logs on your Exchange server will point you in the right direction.Perhaps he has an iPad or some other thing configured and forgot. I would search the logs for his logon name and see what is trying to use ActiveSync.
Donna HSr. Manager of ITAuthor Commented:
Thanks Shaun.

I ran the event comb but I didnt get any results.  I am checking the rest of the solutions in your article.
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Donna HSr. Manager of ITAuthor Commented:
Thanks Jeff,

I will try checking the IIS logs on the Exchange server.
E ATech LeadCommented:
Also these are possibilities about lockout issue,
-Mapped network drives
-Logon scripts that map network drives
-RunAs shortcuts
-Accounts that are used for service account logons
-Processes on the client computers
-Programs that may pass user credentials to a centralized network program or middle-tier application layer
-Active sync devices (cell phone,etc..)  

How to identify the source of Account Lockouts in Active Directory:

Troubleshooting account lockout the Microsoft PSS way:

What are the common root causes of account lockouts and do I resolve them:

Trace the source of a bad password and account lockout in AD:

Hope this helps!

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use PsExec on the users workstation with the -S switch to run under the system context the run the command: cmdkey /list
Shaun VermaakTechnical SpecialistCommented:
Did you enable auditing?
Jeff GloverSr. Systems AdministratorCommented:
One other thing you can look at is his Exchange account (in the EAC). If you select his account, you can see Mobile Devices on the right side. Clicking details will tell you if he has more than one device connected. Since you indicated that the lockout event indicated the Exchange server, you already have all the detail any scripts I use will tell you. From this point, you have to follow the clues.
You could also try to install Network Monitor on your DC's unlock  the account then start the captures  as a last resort
Donna HSr. Manager of ITAuthor Commented:
Shaun,  I have enabled auditing on the client workstation and auditing is turned on for the DC and Exchange servers
Donna HSr. Manager of ITAuthor Commented:

ran psexec,  results showed Currently stored credentials as * NONE*
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