R53 06 Cooper S
 

the other day my serpentine belt disintegrated. i put a new belt on and 2 hours later it did it again. this only happens when i really get on it. but as soon as i put the belt on i really hit it hard and it didnt do it. but 2 hours later it did. what the hell is the problem?

check tensioner bearings I've seen them go and cause the belt to derail and desttroy them ... Also check all components for proper alignment