I've recently upgraded to iPhoto '11 (couldn't resist the pricing on the new app store) and as I'm adding more meta-data to my library and generally organizing things (places, faces, etc... I hadn't upgraded since '08) I've noticed something odd in my photos. Every photo in my library has a description (though many are short), but it would appear that somehow the description of one of the photos has been appended to many.

I don't know if maybe I accidentally screwed up a batch change at some point in the past, or if the library upgrade somehow messed up, or what else may have happened. But what I need to do is fix these somehow.

Now, manually editing is something of a daunting task. Within a library of 21,248 photos, 18,858 of them have this additional text. The one thing I do have going for me is that it's a specific string. If there's a way to "remove this string from everywhere in the library without removing the rest of any given description" then that would be perfect.

Is there anything I can do like this? Maybe even manually editing a library file in a text editor? (Would that break anything else in iPhoto if its library was edited outside of the application, even while it's not running?) Does anybody have any ideas?