what is wrong with iPhoto?

Up until recently, when editing photos, the photo would black out when I try to edit.

I have a Mac OS X

Version 10.7.4

iphoto version 9.3 although continually updated.

I am working with JPEGs and RAW photos and sometimes I am experiencing "technical difficulties"

1. When I select a photo to edit, as soon as I click on an editing selection (QUICK FIX, EFFECTS, ADJUST, or even BOOST, SHADOW) the photo disappears. Now I can go back to the album and re-select the same photo that disappeared and it was edited. So what I am saying is that I cannot watch the process of my photos getting edited. This never has happened before.

PLEASE HELP!!

thank you for your time :-)