OK, I finally identified the problem and have been able to fix it. Essentially, there's a bug in the iPhoto update that was just released to the masses. If there is a TIF image file in the library, iPhoto will go into an endless, CPU-hogging loop if it needs to re-build the thumbnails whenever it encouters the TIF image.
Here's how I found and fixed the problem. After I created a new library, I was finally able to summon the repair dialog by double clicking on the faulty library with the Command+Option keys pressed. I then used the 'Repair Library' option (the one at the bottom of the list). Apparently, this does NOT perform a thumbnail re-build of the library (fortunately!) and I was able to get the entire library up and running. However, when I stopped and started iPhoto again, I was back to where I started, as it immediately wanted to perform a thumbnail rebuild again.
I wanted to find out whether there was a particular object in the library that was causing the problem so I used the following command from within the Terminal app to figure out what was happening:
$ sudo fs_usage -w | grep iPhoto
This basically shows you everything that the iPhoto app is doing on the disk. Much of the information displayed is not relevant but, critically, it does show the path names to the files it's reading (thanks to the -w switch). I found that the problem always kicked in after accessing a particular file - which just happened to be a TIF image.
Next, I used the following command to identify where all the TIF images in y faulty library were:
$ cd <path to my iPhoto library>/Masters
$ find . -name \*.TIF -print
This gave me the path names for a dozen TIF images. Since the path names incoroporate the dd/mm/yy information, I now knew where the suspect offending files were.
I then opened the offending iPhoto library, again with the Command+Option, and once again performed a Repair. This dropped me into the library and I located and removed (after first exporting) all the TIF images and then deleted them from within the library.
That fixed it. I am now able to open the library each time without issue. I will NOT be adding any more TIF images to my library.
Hope this helps others.
- CDM
