Crash! Chunks can become chunks that cause the game to Crash when being loaded.

I was in my survival world in the end and when I went back to the overworld a few seconds later the game freezed and crashed. When I restarted minecraft and entered the world I was in the end again because the game did not save but when I went back to the overworld the game crashed! It happened every time I did this! Then I went back to the overworld and I left the world immediately and then I tryed to enter the world but the game crashed before I Was in the world! Now I am not able to play the world because the game crashes if I try to enter the world!