Superflat "Bed"

Report: http://bit.ly/10FWHyT
So I started a creative world in superflat, redstone ready, but accidentaly set the top 52 block's to "Bed". Then when the world loaded, I went to 15 FPS, then I made the mistake of breaking a "Bed". It was all ok until I hit esc. Then MC crashed.
It may be on more than MC 1.5.2.