Ok, to basics then, Id suggest, Making sure the disc is clean and make sure the drive itself isnt locking up during that process. If that can be ruled out, in one instance, on a very f'd up comp, I had to let that portion run for several hours... maybe more. It took forever but eventually it got through that. If all else fails try another drive. If another drive still doesnt work there is another issue that will need to be solved before hand.