Whenever I try to play 1.7 version or older, Minecraft just stops responding, the screen goes black or white and I can't play. Sometimes it starts loading but I can't move or do anything, and the world does not load. It stops responding immediately. I've tried playing with another account, reinstalling Minecraft, and deleting the old .jar; I have a good pc and I don't have connection problems. What is happening? Why can't I play?