Exits Minecraft automatically at any time

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here
Playing Minecraft HG (Hunger Games) normally
*What actually happened was...:
Describe what happened here
While playing Minecraft Multiplayer then Exited by itself
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...