I was building in my creative flat world, planting carrots. When I placed some next to flowing water, my Minecraft crashed and the world cannot be accessed any more. The crash log is:

http://pastebin.com/sXBKrp86

If I deselect the Minecraft window, it pauses with a black background, and when I close the menu, I can play for ~2-4 seconds, and then it crashes again.