Dead Space 2 Disc 2

When I get to the point where you need to insert disc 2 of dead space, I insert it as told, but then a message comes up asking me to insert the disc again, even though it's already in there. I checked to see if the disc worked on it's own from the dashboard and it does. I can load save files there too. So from disc 2, I loaded the game I was in before on disc 1, so it prompted me to insert disc 1, so I did. And again, it asked me to insert disc 1 again even though it was already in there. So I can boot each disc from the dashboard, but I can't switch discs in the middle of the game, which is a huge issue, considering that's how you make progress. Please help.