For the past week, my world has been having issues. After my computer crashes, the world will not work properly. When I mine a block, it will wait a moment, and the block will pop back into place. If I kill any living entities, I can not collect their drops. When I quit the world, the world is not placed at the top of my singleplayer world list. Now, I loaded the world and everything is blue. The F3 screen shows me falling from my proper coordinates, and then when I hit y = -1.6, I get a Minecraft Crash. This has happened twice. I am only attaching the last crash report. I've already loaded the world in 1.5.1, 1.5.2, and 13w19a. The same issue happens in all of them. I was originally playing in 1.5.2.