iPhoto shows blank squares or the same thumbnail for each photo.

I am on iPhoto 11, 9.2.1 and work on Macbook Pro OS X 10.6.8. My iPhoto has had a complete melt down. When you open it, it either shows blank squares where the photos are or it picks the last photo you look at at displays this for every single photo. If you click to enlarge the photo it will display the correct photo. When I close it everytime it shows that it is updating the library. I have tried shutting down my Mac hoping that it would reset itself. I have checked that it is up t date.