No video?

Download these small files and load into 4.0. Do you see video?

Both files worked for me, preview and export. How about other files?

Thanks for checking those files, which prompted me to try a "repair reinstall." No change.

Then a PROGRAMS & FEATURES uninstall | reboot | fresh install was tested. Solved. Win 7.

Thanks for the help from Borate.

We now know this issue is caused by the left over cache files from the old versions.

To fix the problem you need to clear the cache:

Best regards.