@ abilyk: I've never even heard of that happening before, and it certainly isn't the norm; you may just have a faulty controller.
@ spockblocker: Yes, keeping any system vertical is bad, they are all designed to be kept horizontal. Granted, ps3's aren't as bad as 360's which actually block a fan when upright, but it still causes unnecessary wear on the disk. With the system horizontal, the weight of the disc is spread across the entire surface area, whereas on its side the weight it all on the bottom edge, which will, naturally, wear down with time. Unless the insides of a ps3 are somehow designed to cradle it, which I'd be unaware of.