Nokia MFE: HTTP error code=500 - possible Kerberos issue?

We use MFE on the nokia mobiles to sync our emails on the moves. Recently for reasons unknown they all stopped working.  We can get onto webmail but our mobiles we receive the following error according to the admin_log1.txt

HTTP error code=500
HTTP Server Error 500: Internal Server Error

I confirmed this by running the Exchange Remote Connectivity Analyzer:

Testing Exchange ActiveSync  
  Exchange ActiveSync test Failed
   Test Steps
   Attempting to resolve the host name in DNS.
  Host successfully resolved
   Additional Details
  IP(s) returned:  
 Testing TCP Port 443 on host to ensure it is listening and open.
  The port was opened successfully.
 Testing SSL Certificate for validity.
  The certificate passed all validation requirements.
   Test Steps
   Validating certificate name
  Successfully validated the certificate name
   Additional Details
  Found hostname in Certificate Subject Common name  
 Validating certificate trust for Windows Mobile Devices
  Certificate is trusted and all certificates are present in chain
   Additional Details
  Certificate is trusted for Windows Mobile 5 and Later platforms. Root = OU=Equifax Secure Certificate Authority, O=Equifax, C=US  
 Testing certificate date to ensure validity
  Date Validation passed. The certificate is not expired.
   Additional Details
  Certificate is valid: NotBefore = 9/17/2007 8:23:10 AM, NotAfter = 10/17/2010 8:23:10 AM"  
 Testing Http Authentication Methods for URL 
  Http Authentication Methods are correct
   Additional Details
  Found all expected authentication methods and no disallowed methods. Methods Found: Basic  

 Attempting an ActiveSync session with server
  Errors were encountered while testing the ActiveSync session
   Test Steps
   Attempting to send OPTIONS command to server
  OPTIONS response was successfully received and is valid
   Additional Details
  Headers received: Pragma: no-cache
MS-Server-ActiveSync: 6.5.7638.1
MS-ASProtocolVersions: 1.0,2.0,2.1,2.5
MS-ASProtocolCommands: Sync,SendMail,SmartForward,SmartReply,GetAttachment,GetHierarchy,CreateCollection,DeleteCollection,MoveCollection,FolderSync,FolderCreate,FolderDelete,FolderUpdate,MoveItems,GetItemEstimate,MeetingResponse,ResolveRecipients,ValidateCert,Provision,Search,Notify,Ping
Content-Length: 0
Date: Wed, 31 Mar 2010 08:47:11 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET

 Attempting FolderSync command on ActiveSync session
  FolderSync command test failed
   Tell me more about this issue and how to resolve it
   Additional Details

  Exchange ActiveSync returned an HTTP 500 response.

I cant see any problems on the server APART from the following error Event ID: 4

The kerberos client received a KRB_AP_ERR_MODIFIED error from the server host/  The target name used was ldap/ This indicates that the password used to encrypt the kerberos service ticket is different than that on the target server. Commonly, this is due to identically named  machine accounts in the target realm (CHRISTIEGROUP.COM), and the client realm.   Please contact your system administrator.

Im not sure if this is causeing the problem, if so how can I resolve it?

Thanks for any help given.
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Try to set authentication to integrated.
Use the Exchange System Manager to change it.
Via Servers , Protocols, http
christiegroupAuthor Commented:
I have checked that and far as I can see integrated Windows Authentication box is ticked
christiegroupAuthor Commented:
It was authentication to integrated check box within IIS exchange folder

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
thats what i said!
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Internet / Email Software

From novice to tech pro — start learning today.