I havent gotten it yet so I of course haven't had any problems. Can you take it back? If it was shipped to you, I would try the boiling method. Everything I have gotten in the mail for my Xbox that hasn't worked... was fine after a quick 60 second boil in water.
Bing water to a boil.
Toss disc in.
Wait 60 seconds.
Pull disc out.
Plop into Xbox.
Play.
(If this disc was bent during shipping this will return it to its original flat shape, it will also boil away any debris.)