Sorry for this newb question, but in iPhoto, i go to make a slideshow with a set of images and some of the images won't load into the slideshow. I get this box with an exclamation point on the inside of it and it appears as a black screen in the slideshow. What am i doing wrong? Not all the pictures are doing this, but most are. EDIT - Also, when I try to export my photos as a slideshow to Quicktime, iPhoto just stalls and doesn't do anything.