Black Screen when Joining a Game

When I tried to join a Co-Op Vs. AI, Summoner's Rift 5v5, Intermediate. I received a black screen in which I was unable to select my champion. Upon trying to leave/exit I received a warning that I would receive a penalty, so I sat there hoping it would resolve itself. I minimized the game and reopened it however it still didn't work. It finally put me back to main menu however I still received the time penalty (5mins). I'm fine with the penalty just wanted to allow you to know so you may work on resolving this issue so that It does not happen to other players.