I just started playing SH3 and encounterd the dastardly key code problem. I thought that maybe it was the fact that I had a burner installed, but my friend tested that and with even a DVD burner it installed. What I did do that seems to have cured the problem for installation and the disc check at start-up is to change my DVD drive to the master on the IDE channel. I am not sure if this is the solution, but it worked for me.