Game crashed on multiplayer

Put the summary of the bug you're having here
opened server and game crashed.
What I expected to happen was...:
Describe what you thought should happen here
I expected it to load the server.
What actually happened was...:
Describe what happened here
Open up a multiplayer server(clasicsb.net) and the game acts like it is going to load, the screen turns grey, then it crashed and kicks me out of the game.

Steps to Reproduce:
1. Open Minecraft
2. Click on Multiplayer
3. Open the server(clasicsb.net)