Iphoto screen turns black--- sometimes

Question

Iphoto problem
I'm using Iphoto '11
version 9.2 (626)
MAC OS X Version 10.6.8
Some of the images don't show up at all but come up with a gray dashed border around white background.  When I double click this, instead of an image appearing, the screen in iphoto goes solid black. In looking at the slides on the bottom nest to the "info", 'edit", "create" links, I can see something, at least a small image with some color but can't make out what it is; but there is something there. Then I scroll down in Iphoto and arbitrarily chose another (summer 2006 Feb 14 2006-Jul 20, 2006).  In this photo, I double click and the iphoto screen goes black. Another from the same camera, taken same day will appear, I click on "edit" and the image remains and is editable. The screen is black but I can see the image in that slide bar at the bottom of the screen. I scroll along the images at the bottom and most react as expected but every now and then I click on an image and get the screen black.
Now within these same photos the mystery continues. In most of the "normal" images I can select and drag onto my desktop or put in a folder on my desktop (or anywhere else I designate). But, with these particular images that turn the Iphoto screen black I cannot move them. I tried to email them, they did not appear when the email was received and opened. No photo.
Any help will be most appreciated

Answer 1

Option 1
Back Up and try rebuild the library: hold down the command and option (or alt) keys while launching iPhoto. Use the resulting dialogue to rebuild. Choose to Repair Database. If that doesn't help, then try again, this time using Rebuild Database.
If that fails:
Option 2
Download iPhoto Library Manager and use its rebuild function. (In early versions of Library Manager it's the File -> Rebuild command. In later versions it's under the Library menu.)
This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.
Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.  
Regards
TD