Well I can't believe this happened. Two weeks ago I imported about 7,000 photos into a iMac 2.4Ghz and the total number of photos was over 14,000. I had changed some of the dates that had a 2024 as the year. Then yesterday imported a couple hundred more photos from the camera. Everything seemed OK. This morning the flashing "?" occurred at startup. I restarted holding the "shift" key down into safe boot. Then repaired permissions and restarted and every thing looked normal. This PM I downloaded several more photos from the camera when the problem occurred. iPhoto wanted to resolve some conflict ?? which I clicked OK. Now only 1200 are in iPhoto. I do have a backup from a week ago. What to do??