It could be a combination of the 9.3-your account and the library. If you get a chance copy the library to another account on the iMac and see if it will open there. If it does'nt then it appears it's the application.
However, if the library opens in the other account we're looking at your account as the problem. In that case the first thing to try is make a temporary, backup copy (if you don't already have a backup copy) of the library and 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.
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3 - launch iPhoto and try again.
NOTE: 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.
If that does'nt help the problem it could be another preference file(s), other than iPhoto's, that's causing the issue. There is a way to determine if that's the case:
Trouble Shooting Preferences
1 - close all applications.
2 - open your Library folder, Home/Library, and drag the Preferences folder to the Desktop. A new Preference folder will be immediately created in the Library.
NOTE: if dragging the Preference folder to the desktop only copies the folder then after the copy has been completed go back and drag the contents of the Preferences folder from the Library to the Trash in the dock. You will be asked to enter your Admin password. Then reboot and try again.
3 - run the application again and determine if the problems is fixed.
4 - If the problem is fixed:
A - open the working Preferences folder (HD/Users/your_name/Library/Preferences).
B - Open the Preferences folder on the Desktop, select all of the contents and drag them into the working Preferences folder.
C - When the Copy window pops up check the "Apply to All" check box and then click on the Don't Replace or Skip button.
5 - If the problem is NOT fixed, drag the contents of the Preference folder on the Desktop into the Preference of the Library folder are replace the new one that was created by clicking on Replace.