When playing single player, or multiplayer the game sometimes will freeze, and then allow me to play again. It will do this a couple of times and then freeze completely.. This prevents me from accessing the OS to kill the process, so I have to hard restart my laptop.

This does not happen when playing 1.6.4 only since I've moved to 1.7. I've attempted to assign more memory to the process but this doesn't help. I've also reduced the video settings, and while this seems to have helped it does not correct the issue.