Random CTD While playing with normal generation

Put the summary of the bug you're having here

What I expected to happen was...:
Play the game?

What actually happened was...:
If playing in a regular generation world, you can suddenly get a CTD while playing (no specific reason detected, but I'd say it happens while loading some specific chunks, varying each time...). If I load a superflat world nothign happens, and I haven't tested AMPLIFIED or customized generation...

Steps to Reproduce:
1. Load/create a new world in Default generation.
2. Move around, load new chunks
3. Eventually you get the CTD