Problem with AutoCAD Mechanical 2015 offline help

I am currently building a new 64bit Windows 7 image for deployment across our engineering college, I have downloaded and installed the offline help files for AutoCAD mechanical 2015. The Add/Remove programs wizard is showing the help files as installed, the options dialog for the help files is pointing to the correct location and that location is in the Trusted Folders list.

However, when I click on the Help option, or press F1, the Help window opens but is completely blank. I can navigate to the folder and launch the 'index.html' file in a web browser and navigate the files just fine that way, but they will not work in the Help dialog.

Has anyone got any ideas that I could try??