Put the summary of the bug you're having here
What I expected to happen was...:
log in to my survival game and normally play my world like i have in many other snapshots and regular updates
What actually happened was...:
it sent me back to the home screen of minecraft and after one or two tries it crashed my game
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...
Environment
Put your operating system (Windows 7, Windows XP, OSX) and Java version if you know it here
This has happened before and usually i can just restart my computer and it will work completely fine but i cant do that this time. Sometimes in the past it logs me on and i can move but chunks wont load at all, i cant open chests, mobs will be frozen, and blocks wont drop when broken. Also I can go on another copy of my world but that backup was made before this snapshot, 13w2 or 3 im sorry i forget