[CLIENT] Screen Goes Black During Champion Select.

Sometimes when I go into the champion select after proceeding with the AFK check, the LOL window goes black and I am unable to make any adjustments to my runes/masteries/summoner spells etc. The sound goes off to let you know you're in the champion select, but the screen turns black. I don't know any other way to get out of it than to exit the game. Unfortunately, it reports me as an AFK-er and I get banned for 5/10/15 minutes.