Game crashes when trying to load a world.

Put the summary of the bug you're having here
The game starts fine, however whenever I go to load a world or create a new world it will crash before I get there. It says loading world then will go unresponsive before crashing. I have the most recent version of java and have even tried uninstalling it to use older versions but can't figure out what's going on.

What I expected to happen was...:
Describe what you thought should happen here
I expected the game to start normally...

What actually happened was...:
Describe what happened here
Game starts fine. When loading a world or creating a world the game crashes before I can get there. It will begin loading terrain then go unresponsive ("not responding") then crash and pull up a report.

Steps to Reproduce:
1. Start game with Minecraft launcher
2. Select single player
3. load previous world or create new one