Maybe your iso gone faulty when using XIso (that program is baad, believe me, of you do not read here
why xiso is not to be used )
I say that you should redo the whole iso creation process. Grab the files again, make a new iso using Craxtion or similiar. The absolute best would be if you could get your hands on one of the layout files that are avaible at xbox-scene (no idea if there is one for this game though).
Craxtion is real easy to use and always works good.