I was playing harcore single player, and everything but the chunk I was on dissapeared. No matter how many times I log out and back on, it's still gone.

Put the summary of the bug you're having here
All chunks, except for the one I was in, vanished.
When this happened, I got intensive lag, and teleported around.
When I jump into the void, I do a longer than normal fall, and teleported out.

What I expected to happen was...:
Describe what you thought should happen here
I was about to head back into a ravine one chunk away.

What actually happened was...:
Describe what happened here
But it vanished. When I logged off and went back on, every other chunk vanished too.

Steps to Reproduce:
1. I have a video here. It's a part of a series, so I made fun of it at the time.
http://www.youtube.com/watch?v=Gy_wR2ETKhY
The glitch doesn't happen until I grew carrots at 36:40