Calendar appointments showing 1 hour later on recipients’ calendar appointments

      Symptom: Any calendaring client may show 1 hour later on a recipients’ calendar appointment (Outlook, OWA, Blackberry or Goode devices etc.).  The recipient will appear to not follow DST2007 rules.  This is true even with OS patches are successfully applied even with rebasing successfully executed.  Warning: If the system is not OS-patched or rebased successfully, the symptoms will appear similar to this issue (and the unpatched OS is much more common). 


·         Explanation: This is caused due to multiple copies of CDO.dll or CDOEX.dll existing on the Exchange and/or BES/Goode servers , and the copy  of CDO.dll or CDOEX.dll is not being updated, but the applications (Outlook, OWA, Blackberry, Goode, etc) are using the older version of the dll. This can be created by several applications (unrelated to messaging potentially) which install or copy CDO.dll or CDOEX.dll to a separate directory, then register that rough dll. 


·         Solution:

o   Determine if you have this specific issue,

§  please verify all patches and rebasing issues are successfully applied (for example is the OS clock correct, are meetings the user organized being rebased successfully).  If the systems are not properly patched or rebased, the symptoms may appear similar. 

§  Verify that if a user who is patched sends an appointment to another user who is patched, that the recipient user is showing that appointment one hour later than originator’s. 

§  Search the Exchange server (and BES server etc) for multiple copies of CDO.dll or CDOEX.dll.

1 – Run this: C:\>dir /s cdo.dll

2 – Repeat for all drives.

3 – If there’s more than one cdo.dll, you have a problem

Same for cdoex.dll

o   Fix:

Exchange 5.5 (CDO.dll only – 5.5 does not use/ship CDOEX.dll)

(note – path to system32 may vary)

1 – c:\winnt\system32\cdo.dll is the correct CDO.dll. Delete all other copies of CDO.dll.

2 – regsvr32 “c:\winnt\system32\cdo.dll”


Exchange 2000/2003 CDO.dll

(again – paths may vary slightly depending on installation)

1 – c:\program files\exchsrvr\bin\cdo.dll is the correct CDO.dll. Delete all other copies of CDO.dll.

2 – regsvr32 “c:\program files\exchsrvr\bin\cdo.dll”


Exchange 2000/2003 CDOEX.dll

1 – c:\Program Files\Common Files\Microsoft Shared\CDO\CDOEX.dll is the correct CDOEX.dll. Delete all other copies of CDOEX.dll.

2 – regsvr32 “c:\Program Files\Common Files\Microsoft Shared\CDO\CDOEX.dll”

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