Today I was trying to back my iPhoto library (10.7, iPhoto 11) (less than 5 GB) to Amazon's cloud service. I needed to access the pictures from a different computer for a university project. I noticed Amazon was giving me errors...and when I tried to reopen iPhoto, all photos were gone and I saw nothing but the "To get started..." screen. What's strange is that the iPhoto library's size didn't change, and opening "All my files" in Finder still shows some of the pictures. I tried backing up from Time Machine, but iPhoto wouldn't display anything other than the "To get started..." screen. Thank heavens that I backed up everything on Time Machine...but trying to bring back an earlier version of the library didn't satisfy iPhoto. What did I do?