minecraft keeps freezing up and shutting down

I open a world on minecraft: windows 10 beta and it sometimes stops doing anything. I can't move open crafting or the menu. Sometimes after a few minutes the window disappears. Then after a moment the icon on the task bar also disappears. I have no idea what causes it. I have no idea how not to duplicate it. Sometimes it happens even before the world finishes opening up. and sometimes after it has been going for awhile. It started a couple of weeks after buying the game, so why did it go 2 weeks and suddenly stop working correctly?