Minecraft always crashed when i start it.

Put the summary of the bug you're having here

*What I expected to happen was...:*I logget in and go to the start screen
Describe what you thought should happen here
To come to the selection screen
What actually happened was...: My Minecraft has crashed in few seconds after the selection screen
Describe what happened here
Minecraft is crashed
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...