IPhoto refuses to open

Question

I've tried everything else, so now I'm coming here.
One day, with no apparent cause (no new downloads, no system changes, no updates) iPhoto stopped opening.  The icon is still there at the bottom of my screen.  I click on it, it bounces as if it's working, and the iPhoto toolbar appears at the top of the screen.
However, the iPhoto screen itself never appears and all the items in the toolbar are greyed out (unselectable).  Has anybody else run into this problem?
Potentially related:  I've been doing updates on my wife's macbook air, which included doing an update to her iPhoto (which works fine).  In the app store, under iPhoto, it gives her the option to update.  When I go to the app store on my computer, it gives me the option to purchase iPhoto for $14.99.  Both of us are using the iPhoto that came with our respective computers.  Could this be the culprit?  The fact that apple doesn't seem to recognize that I do, in fact, own this software?
Thank you all, in advance.

Answer 1

Try the following:
1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your
     User/Home/Library/ Preferences folder.
2 - delete iPhoto's cache file, Cache.db, that is located in your
User/Home/Library/Caches/com.apple.iPhoto folder (Snow Leopard and Earlier).
or with Lion and Mt. Lion from the User/Library/Containers/com.apple.iPhoto/
Data/Library/Caches/com.apple.iPhoto folder
3 - launch iPhoto and try again.
NOTE 1: If you're moved your library from its default location in your Home/Pictures folder you will have to point iPhoto to its new location when you next open iPhoto by holding down the Option key when launching iPhoto.  You'll also have to reset the iPhoto's various preferences.
NOTE 2:  In Lion and Mountain Lion the Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and hit the Enter button - 10.7: Un-hide the User Library folder.
OT