iPhoto 9.5 quit working

I was using my iPhoto today just fine, but had to quit and do some other things for a while. When I tried to open iPhoto again a little later, the following message popped up. "You can’t open the application “iPhoto” because it is not supported on this type of Mac." The icon now has the "Don't" symbol (circle w/a slash) on it. I have tried to open it up in various ways to see if it was an icon problem, but it wasn't. I really don't know what to do, and don't want to lose all of my pictures.

Help!