Missing Aperture 2 photos, all of them?

One day when I opened Aperture and clicked on a project, I got the "Loading Photos" spinning tick-mark icon for 1/2 hour, and no photos in any album, project, library, etc. I had the hardware checked at the Apple store, installed a new OS, reinstalled Aperture, and pointed it at it's original library and also at it's backup library, (which are both still 60 gigs) and got nothing. Any ideas?