Screwed up halo 2 campaign...

[diamondman]

I am new and just got my hands on insolence. I couldn't do something as great to multiplayer as some of the ppf files I find do, so I modified a single player map (oldbombayas.map or something to that effect) to have a 5 shot burst sniper rifle with infinate ammo and increased zoom. I loaded the map and the level wasn't completely pieced togeather while cortona (forgive spelling) yells for you to wake up. You could see through the wall and guns were running around with no marienes holding them. After this loaded once I moved around for a while. I stole johnson's sniper rifle and went around the corner when the game froze for 5 seconds then started with models missing! this continued, so I played another level, the same, multiplayer runs fine, I deleted the cauch and the same happened, so I played it off the disk after deleting the cauch to the same result. I got rid of the whole halo 2 game, cauch, the C drive and E drive, replacing the C and E(sav files) with a backup i had then playing off the disk. Same happened again! I must mention that I replaced the hard drive with a used (old) 20 Gb hd and am on vacation so I am far from the origeonal drive, but it worked right until i played that modded map. How do I get rid of this problem with out getting a new box.