"Iphoto quit unexpectedly" but I don't know why

Iphoto comes up with this message everytime I try to open it. The application doesn't even open, this message comes up instead. I can copy the problem details and system configuration if that would help.

I've repaired disc permissions, I've deleted the com.apple.iPhoto.plist file from library>>preferences, and I've also deleted the iPhoto file from library>>caches.

I didn't change anything on my computer when it started doing this (around November?). The only thing that I can think of that happened around the same time was that my external hard drive crashed and now no longer works (so I am a bit worried about my backups and don't want to mess arounds with reinstalling if possible). I am not sure if the two events were connected because I didn't try to open iPhoto until a few weeks later.

I use a MacBook 7 with OS X version 10.6.8 and iPhoto version 8.1.2

Any ideas? Thanks.