Strange screen problem (related to Mac Crashes?)

Here's the background: While playing a summoner's rift game, my game crashed due to the mac problems. Upon reconnecting, my screen promptly reverted to solid black with white cloud shapes(save tower health bars, champion health bars, and HUD). I could still move around and use abilities, but could not see my champion.

After a short while, Images started flashing on the screen. Among these were a face and a couple swords, all of these images were very grainy and pixellated as well.

I was able to screenshot some of the images before the game crashed again, and I haven't encountered the problem since.