After installing Snow Leopard on my Macbook Pro, I immediately noticed problems with iPhoto '09. What I normally do when backing up my computer is copy the iPhoto package file over to my external hard drive. Once I've reinstalled the OS, I simply drag the iPhoto package file back onto my Macbook Pro. In the past, this worked great, but with Snow Leopard, I definitely had issues. If you encountered this problem, this information will be useful to you…

If you backup your Mac the same way, you first want to drag the iPhoto 09' package file from your external hard drive into your "Pictures" folder on your computer. Once you've done this, DONT open iPhoto - instead, navigate to your "Pictures" folder where you just put the new file and right click on it. Select "Open Package Contents" and find the file "iPhotoMain.db."

Now, move the "iPhotoMain.db" file onto your desktop (instead of deleting it, so you can revert back just in case). Now all you have to do is click on iPhoto from your dock while holding down Command and Option at the same time. It should pull up iPhoto with the following message: "Rebuild the iPhoto Library database." Check all the rebuilding options and click to rebuild. This will take time depending on how extensive your iPhoto library is, but this should work for you. If not, let me know in the comments!