I just purchased the game of Minecraft, excited to play after hearing great things about the game. Following the download I opened minecraft up and selected single player. I got to where I created a new world and when it loaded the texture I got a black screen and I do no matter how I try to play the game. This is very frustrating because I just spent $21 on a game that isn't running. I have heard though that single player isn't working currently. What am I to do?

(I'm running Mac OS X 10.5.8)