Upon start-up it downloaded the newest update (1.4.7). I logged onto my redstone world to do some work and started going back and forth between world. After about the 2nd or 3rd time back; all my work was gone except in the chunk I was in.At the edge of the chunk there was a floating redstone torch. I saved and quit then came back in a new chunk and that chunk and the previous chunk were loaded properly. I did this in a couple of chunks but upon returning about the forth time updating chunks the game crashed! When i came back to see if my work was still there only 2 chunks were "up to date" the flouting torch chunk was one of them but the torch was missing; In the other chunk there was redstone that was powered improperly. The rest I didn't work on so i couldn't say (except one which was a ways away but was fully updated(I filled a pond)).

This is not a duplicate of "Out of memory when spawning a ghast in farlands".
The entity being ticked was me the player and not a ghast. Which caused the crash in that bug.

Crash log in attachments.

Key for picture
Green: previously And gates.
Purple: improperly powered.
Blue: on the chunk border extended to the right.