i had this same shit with nfsmw , i am very carefull with my games , my system is always in the lie down position , and it never gets moved , my game developed 2 cracks on the top surface on the disc , like they had happened when there was force used to put the game into the case(altho this was never the case) , the cracks got bigger until one day 2 or 3 achievments from completeing the game , it froze , the cracks had spread to the underside (im assuming the heat in the drive makes em worse) , anyway , short of it is that i was not happy @ losing a 50 quid game , so sadly i snapped it into small pieces in a rage lol