*****latest update: problem solved by reinstalling mountain lion. Moderator, please help delete this thread, thanks I'm running ML on a rMBP. I noticed that whenever my VLC is opened (regardless of whether a movie is running, VLC is active or just in the background), opening the launchpad will lead to pixel rendering problem where there are tiny red flickering pixelated squares on the screen which disappear soon after emerging. Sometimes they will stay on though (shown in the image). Anyone has an idea of what's going on? I hope it's not a hardware problem as I'm nearing the 14th day of return period.