My new halo 3 disk keeps jumping back?

[Swish]

I knocked over the xbox and the halo3 disk got a huge circle scratch and disk wouldnt play anymore I tried other games I got with the 360 and they worked but just not Halo. I got a new halo 3 disk and i started. Now to the problem.. i had 8 things unlocked with the old disc, so it was stored in the hard disk . There is a section in halo 3 where you rescue kartana and go to the snow mountain. I was there and on third objective. ON the new disc, EVERYTIME I DIED it kept going back to start and not only that it kept repeating itself. It played the movie of me going to the mountain, and then it played movie again and again....if i restarted the console there i was in the third objective and if i died boom the movie of me coming to mountain kept repeating. Soi guess deleting the game in the harddrive game section would give me a fresh start. So i went to harddrive and deleted the halo3game. Now i started halo 3 and hit start new solo game.IT KEEPS REPEATINg and game would not move on