This problem may be caused by a variety of factors, including incorrect permissions on required files for the OWA client, registry changes, or damaged files. This article discusses how to troubleshoot this problem.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
These are the subkeys for Cdohtml.dll. You can export each of these subkeys and then run Regsvr32.exe on the DLL to register each key back into the registry correctly. To export and remove the registry subkey, follow these steps:
Click Start, click Run, type regedit to start Registry Editor, and then click OK.
In Registry Editor, select the key that you want to back up.
On the Registry menu, click Export Registry File.
In the Save In list, select the folder where you want to save the backup.
In the File Name box, type a name for your backup file, such as Options or Backup.
Under Export Range, click Selected branch.
Click Save. The file is saved with a .reg extension.
Select the subkey that you want to remove.
If you have OWA 5.5 and OWA 5.5 SP1 installed, select the following subkey:
Press DELETE. Alternatively, right-click each subkey, and then click Delete.
Quit Registry Editor.
When you are finished, stop the WWW Service by using either the
Services component in Control Panel or the Internet Information Services
(IIS) Manager. Then you must re-register Cdohtml.dll. To do so, follow these steps:
Click Start, and then click Run.
, and then click OK.
After you re-register the Cdohtml.dll file, you may have to verify the permissions on the registry subkeys. To verify the permissions, follow these steps:
Click each subkey, click Security, and then click Permissions.
Assign the Everyone group Full Control permissions to the registry subkeys.
Assign the IUSR_ServerName account Full Control permissions to the registry subkeys.
Restart the WWW Service.
Confirm whether there is an apostrophe in the name of the directory where OWA was
is the case, remove the OWA component and reinstall it in a different
For additional information about how to remove and reinstall OWA, click the following article number to view the article in the Microsoft Knowledge Base: