Today I found that when I click on a thumbnail in iPhoto 09 I get an image that is different than I clicked on and when I click to go back to thumbnails area the proper image shows in the thumbnail area for about a quarter second and then it reverts to the wrong image …

The problem is in iPhoto cache and we have to rebuild the thumbnail cache! To do so close iPhoto, hold down cmd-opt-shift, then open iPhoto you will see the following message appears on the screen, then you can rebuild whole library!

Note that rebuild process can take quite a lot of time, anywhere from 5 mins to several hours according to library size and selected options.

After clicking rebuild, iPhoto will start rebuilding library.