Xbox 360 freezing in gears of war 2?

Hey fella's Heres my question, Ive got a 360 that has so far worked fine, since i got it back from MS for the RROD. until i got a copy of gears of war 2. I replaced the copy twice so far, for freezing on me during gameplay. and sometimes I get "disc unreadable" and it brings me back to the dash board. But I can play halo3 and my other games till the cows come home. Id like to contact epic somehow and complain or just let them be aware of the issue. I did all the tricks .. i think.. I did hard drive cahe trick, and the reset graphics trick, holding y and right trigger at start up.. nothing worked. the xbox is cool and in open spaces. cant take to MS my warrenty is up, but my other games work fine... sigh...