Activision has acknowledged that "some consumers" who purchased Guitar Hero: Warriors of Rock are experiencing a disc read issue and the company is taking "immediate action" to rectify the situation. Folks who are having a problem should call Activision's customer service center at 800-225-6588. The publisher states that it will "offer existing customers free replacement discs in exchange for any purchased defective disc."

Joystiq learned of the issue earlier this week and contacted Activision after several reports and one retail tipster told us that his store had received "40 returns" in one day.
Source- Joystiq