Make a temporary, backup copy (if you don't already have a backup copy) of your library and apply the three fixes in order as necessary.
Fix #1
1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your HD/User/Home(
)/ Library/Preferences folder.
2 - delete iPhoto's cache file, Cache.db, that is located in your HD/User/Home()/Library /Caches/com.apple.iPhoto folder.
3 - launch iPhoto and try again.
NOTE: If you're moved your library from its default location in your Home/Pictures folder you will have to point iPhoto to its new location when you next open iPhoto by holding down the Option key when launching iPhoto. You'll also have to reset the iPhoto's various preferences.
Fix #2
Launch iPhoto with the Command+Option keys held down and rebuild the library.
Select the options identified in the screenshot.
Fix #3
Using iPhoto Library Manager to Rebuild Your iPhoto Library
Download iPhoto Library Manager and launch.
Click on the Add Library button, navigate to your Home/Pictures folder and select your iPhoto Library folder.
Now that the library is listed in the left hand pane of iPLM, click on your library and go to the File ➙ Rebuild Library menu option
In the next window name the new library and select the location you want it to be placed.
Click on the Create button.
Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments but not books, calendars or slideshows. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.
OT
