Halo 3 OSDT KIZINGO BLVD GAUSS TURRET ERROR?

i had this problem when i go inspect the gauss turret it shows a scene..but then an error shows, it says wipe the game cd and restart console. I did the instructions and yet the error still came up. I even went back and traded for a different game cd just in case it was the problem but it wasnt..Anyone know what to do?