Something similar happened to me. I was playing through the start, and at the end when you finally stop using that noob Roxas, I accidently knocked my PS2 from standing up posistion to the floor. I thought nothing of it since the game kept going. So I keep playing and decided to take a break. Next time I pop in the disc and during the next movie scene, it decides to not load. If you still have you receipt, go to the retailer you bought it from and state that it was clearly like that when you purchased it. They may give you your money back/a brand new copy.