Grey photo boxes
I have 30,000+ photos and some (photos and clips) appear as grey boxes in random clusters within events. I thought it may be to do with duplicate file names but I tried searching against an affected file name in finder and no duplicate so not sure that is it. If I allocate a face I can then view in Faces, and if I click on the filename in finder it opens in preview, so they are there. Any simple solutions to ensure all photos view in iPhoto?
MacBook, OS X Yosemite (10.10.2)