I put all my games inside sleeves inside the game case now, seems to have worked. 2 of my games cracked, pretty pissed off. One was Reach and of course MS wants me to pay $20 for a replacement....
I think they use cheaper discs nowadays, because I checked some of my Xbox games like halo 2 that I played the hell out of... It's scratched to shit, still works, but no cracks.