My x box 360 is leaving a ring looking scratch in the middle of the cd

game stops playing in the middle of game every time

Well for starters, stop putting discs in it. You're going to have to send it in for repairs, there's something inside the tray rubbing against the disc that needs to be replaced.

That can't be fixed. You need to buy a new game, and/or buy a new XBOX 360. Send it to Microsoft in America, without voiding the warrenty and you should be fine, and by voiding the warrenty I mean, Taking the case off and trying to fix it yourself.