Since you've narrowed down the problem to something in your primary user account the following may let you determine what it could be, possible a preference file.
First delete the iPhoto preference file,
com.apple.iPhoto.plist, that resides in your User/Library/Preferences folder 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 the the Option key. You'll also have to reset the iPhoto's various preferences.
If the above didn't help it could be a preference file other than iPhoto's that's the culprit. Therefore
Trouble Shooting Preferences
1 - close all applications.
2 - open the Library folder in your Home account, Home/Library, and drag the Preferences folder to the Desktop. A new Preference folder will be immediately created in the Library.
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 button.
Click to view full size
5 - If the problem is
NOT fixed, drag the Preferencess folder on the Desktop into the Library to replace the new one that was created.
Happy Holidays
