It's strange.

 
In the Microsoft Kb:

"Microsoft XML Core Services (MSXML) 4.0 is installed in side-by-side mode. This means that installing MSXML 4.0 does not replace or depend on any previously installed version of the MSXML parser on your computer. This is done to protect the quality of applications that are currently using Msxml.dll, Msxml2.dll, or Msxml3.dll. Side-by-side mode also allows you to decide which version of the parser to use in your code. "

It looks like the progid in the registry(hkey_classes_root)  of the problematic machine has been modified.