Failed to call MS XML parser Class not registered

I receive the following error message from the Popup Client interface:

"Failed to call MS XML parser Class not registered"

Install Microsoft Core XML Services (MSXML) 6.0, available at:

http://www.microsoft.com/downloads/details.aspx?familyid=993c0bcf-3bcf-4009-be21-27e85e1857b1&displaylang=en