Put the summary of the bug you're having here
What I expected to happen was...:
Describe what you thought should happen here
What actually happened was...:
Describe what happened here
Steps to Reproduce:
1. you would try and load a world
2. when it was almost done it crash
3. the crash report is below
Environment
OS: Windows 7 (ver 6.1, arch x86)
Java: 1.7.0_25 (by Oracle Corporation)
Launcher: 1.2.5 (bootstrap 5)
Minecraft: 1.6.4 (updated Fri Sep 20 01:52:37 EST 2013)
i cannot start the worlds up