Lately, whenever I open iPhoto, it asks to update thumbnails, to which I normally select "later" - but then it starts the revolving wheel indicating that it's working on something behind the scenes. But it goes on forever. I've forced quit the application, and re-opened it only to have the issue happen again. I'm afraid of deleting the app and re-installing because I don't want to lose everything that I've already done/organized in iPhoto. Any ideas or suggestions on how to resolve? Thanks!