iphoto '09 on my MBP 2011 hangs every time I try to add music to a slideshow. When I click "music" it does nothing but show the rotating ball I have to force quit iphoto. Updated OS recently to Mountain Lion. Don't have problem with iMovie and iTunes.

Try this: launch iPhoto with the Option key held down and create a new, test library. Import some photos and check to see if the same problem persists. If it does try this basic troubleshooting fix: 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.

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

Download and reapply the following updaters:

OS X Mountain Lion Update v10.8.2 (Combo)

OS X Mountain Lion 10.8.2 Supplemental Update

iPhoto 8.1.2

Then repair disk permissions and reboot. See if that helps.

Upgrading to iPhoto 11 won't fix the library. Before you try that do the following: make a temporary, backup copy of your library if you don't already have one (Control-click on the library and select Duplicate from the contextual menu) and apply the two fixes below in order as needed:

Fix #1

Launch iPhoto with the Command+Option keys held down and rebuild the library.

Select the options identified in the screenshot.

Fix #2

Using iPhoto Library Manager to Rebuild Your iPhoto Library

Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments but not books, calendars or slideshows. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.

One more try:

Starting over from scratch with new library

Start over with a new library and import the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from your original library as follows:

1. Open the library package like this.

2. Launch iPhoto with the Option key held down and, when asked, select the option to create a new library.

3. Drag the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from the open iPhoto Library package into the open iPhoto window.

This will create a new library with the same Events (but not necessarily the same Event names) as the original library but will not keep the metadata, albums, books slideshows and other projects.

Note: your current library will be left untouched for further attempts at a fix if so desired.

One more attempt: delete the com.apple.iPhoto.plist and com.apple.iApps.plist preference files and the iPhoto cahce file that's in the Home/Library/Caches/com.apple.iPhoto folder. Then open iTunes followed by iPhoto.