I seem to have found a solution:
a) Run PPro as administrator and load the project. It now loads fine.
b) Save the project under a new name.
c) Run PPro as normal user and load the new project.
This is really strange that PPro hanged on this file when I wasn't running it as admin but once the file is resaved I can load it as a normal user.
Try creating a new project and importing the old one into it just to make sure you dont have some corrupted media in the timeline.
Just a thought here, and maybe moot, since you found a viable workaround, but as John T. mentions, there can be all sorts of odd behaviors, when not running as Administrator, regarding permissions.
Had you not found the "cure," my suggestion would be to Move the Assets (so that PrPro could not find them), then Open the Project. When PrPro asks "Where is file ____ ?" I would point it to the requested file, in the new location. I would have placed each file type into a separate folder, so that I would then have to locate each initial file's folder (PrPro will then survey that folder, and re-link to every used Asset in it), and monitor the loading progress. If it hung, on say my PSD Still Images, I would know that something was wrong there.
Still, you found the way to get the Project loaded, so that little test is not useful now.