Exporting videos and photos to a new slideshow in iPhoto

While exporting 3400 photos and videos to a slideshow in iPhoto on the MacBook pro, half way through the small export screen remains black, and the green bar does not seem to be moving forward, but it could just be very slow. FYI, I have exported large files before, and while it has taken sometimes 24 hours to process, export never stopped, although as I stated, I am not certain that it has stopped. Could there be a problem with a photo or video on the file??

I would appreciate any insight. Thanks!