An update is available to enable trust to user specified protocol handlers in the 2007 Office system

To resolve this problem, apply the following hotfix package:

981041 Description of the 2007 Office system hotfix package (Mso-x-none.msp): April 27, 2010

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To activate this hotfix, create a registry sub key with the name custom_prot: at the following location:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Common\Security\Trusted Protocols\All Applications\

where custom_prot: is the actual protocol handler prefix.

For example, if you want to add an xyz: protocol handler, the subkey should appear as follows:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Common\Security\Trusted Protocols\All Applications\xyz:

Note: the colon (:) character should be included at the end of the protocol handler name. If any registry subkeys in the path shown above do not exist, you must manually create them.