I'm creating a new topic for clarity:
I've tried using the MediaCreation tool from this link
on both my Win 7 64Pro and my Win 8.1 Home machines. In both cases, the exe downloads, but trying to open it (as either user or "Run as Admin") does nothing other than bring up the UAC dialog box
Selecting "Yes" sees the dialog box disappear, and that's it. Nothing else happens at all. Task manager shows no new applications or processes started. What am I doing wrong?