Whenever I try to enter one of my own worlds, it keeps shutting down and showing "java runtime error

Put the summary of the bug you're having here

What I expected to happen was...:
When I click on my world, I would expect the computer to load the world and I would be able to play it.

What actually happened was...:
the computer would load a Minecraft world. Then the computer would shut down Minecraft and say "A fatal error has been detected by the java runtime environment

Steps to Reproduce:
1. open minecraft on the desktop
2. click "play"
3. select a world
4. let the world load
5. you should see the error notice after that
3. ...