iPhoto is generally a very reliable photo manager and organiser on the Mac and you will not normally experience any problems with it. There are many iPhoto users who have thousands of photos and it's ability to cope with large albums is well appreciated by enthusiastic digital photographers.
If something should go wrong, however, and iPhoto isn't behaving as it normally does then it might be possible to fix the fault using a special startup key combination that isn't well known.
Click the iPhoto icon in the Dock or double click it in the Applications folder to start it and straight away hold down the Command and Option keys.
As iPhoto loads it detects this key combo and after a few seconds it displays a window with several repair options that might be useful for fixing whatever fault you have with the application or your photos.
All the functions in the repair window that is displayed are dedicated to rebuilding the contents of the photo library in some way.
You can examine and repair permissions, rebuild thumbnail images from the original images, check the database and repair it if there is a problem, and completely rebuild the database.
The option you choose in the repair window will depend on the fault that is occuring in iPhoto and you might need just one or you might need to use them all. It is best to try each of the functions in the order they are listed and the last one should be used as a last resort.
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