Can't load or create single player world

I am unable to load or create single player worlds. When I try to load an existing world the game goes to load, but after 5-10 seconds of loading the game stops responding. I can 'create' a new world per se, but all I get is complete black void with no actual blocks. After 10 seconds of sitting in the void world, java/the game stops working. (I usually play with Optifine. Attempted on complete vanilla, same outcome)