Launch it from your Start menu, not the old gmechanism icon.
That doesn't work either. Like I said it just..doesn't run :l I ran it from the Start Menu, from Windows Explorer, and the Installer.
Try deleting anything related to your GMech installation, then download it from Luke's website. That worked for me.
It's an installer because it's in Studio now. Also, if there are problems with the installer it's YYG's fault.
Can't you just export it as a ZIP file? It doesn't have to be an installer.