ok first of all where did you buy it from becaue they may have a 2 year store warentee
and if not then you pay sony $150 then they send you a box you put it in, say that COD4 is in it, and send it back. Then they send you either it fixed or replacement. The whole process takes anywhere from 1 to i think 3 weeks, it sucks it has happened to me.
Im sorry dude best of luck.