Most likely (my own theory btw) is the breakpoint between layers on your backup not the same as the original. Therefore it jumps to the next layer and finds nothing... or something... ahh I don't know... :P
Anyway Halo2 can easily be fitten onto a standard DVD5 by removing dashupdate, replacing attractions.bik with a dummyfile and some more file I don't remember for the moment... Simple!
Rallisport Challenge 2 is tougher, but I've played it from my HDD and that works fine...
