IPhoto Crash

Help! I am a pro photographer and PC user newly converted to Mac...on shoot in Naples Italy.... ...Photos backed up on external drive...but images also imported into IPhotos-crashes and won't open....I want to use IPhoto to show images to client....(Thank goodness all images are backed up on external drive so I am not freaking out!) Help me love my mac again

You want to start with a repair of the library:
iPhoto 6 and later: Rebuilding the iPhoto library