Something Strange Happens

Today Something very strange happens in my new minecraft world

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I was playing with my cousin in new world we made and it was survival. My cousin gathered wood and made two wooden pics. Then he started digging down but the ho got bored and asked me to help him climb up to the surface. I started breaking blocks to make stairs but then i got bored and i putted to creative and started breaking block and flying up. But then i couldnt break any block and i wasnt able to move left and right, only up and down. I putted a torch on the wall and i saw that the block i couldnt break was dirt! I went on the surface and my cousin continued playing. After a while he wanted to put on the jukebox the disk 11. We heard it all (I have heard it again) and after 2 seconds the game crashed. I am not lying and this happens today 28/11/2013. If someone nows pls say it in the comments and help me.