I was playing Sonic the Hedgehog, when all of a sudden my 360 froze, I went to take a look at it and was overheating 'cause it was close to a wall, I picked it up and move it away from the way when all of a sudden a heard the 360 scratching the disk!  I quickly took it out and there were two rings of scratch marks on the disk.  I was able to wipe away one of the scratch rings, but the other one wouldn't come, I popped the game back in and I was realeaved that it still worked.  So my advice to all you 360 owners: never put your 360 in a crowded area, and never pick it up while it's on.