This has been happening since I migrated my Aperture library from my old 2011 MBA to my brand new rMBP 2014 two weeks ago. First it started with only a handful photos, which I deleted, but the more times passes, the more projects get infested. Initially I thought it was a GPU problem, but since the computer displays images online and elsewhere correctly, I don't think it is. I read here https://discussions.apple.com/thread/3168022?start=45&tstart=0 that it could be an issue of bad RAM, but in order to download MEMTEST one needs to register and for some reason their stupidass captcha doesn't work ... so I can't do this. On top of everything, I'm currently writing my dissertation and can under no circumstances ship the Mac off to Apple for two weeks, so I'm praying it is software related. Has anyone experienced this before? PS: When I click on the photos, most are still displayed correctly in the Viewer.