it opens a window that says Iphoto has unexpectedly quit...
this window will contain a crash log - please post this crash report here - the first 50 to 60 lines only, please. Copy and paste the text into your post.
What is your iPhoto version? And what have you been doing, before the crashes started? Imported images, moved the iPhoto library to another folder, upgraded software? Is iPhoto the only application that is crashing?
BTW - this is the forum for iPhoto on IOS Devices, not for iPhoto on the Mac. I will ask the hosts to move your post to the iLife iPhoto forum.