Guys I request to please read the question first before jumping to the conclusion that the play disc must NOT be installed.
I got a brand new Xbox 360 Slim 4 GB, and a new GTA 5 game.
The first disc installed perfectly on a pen drive but the second disc is unreadable. Sometimes it runs, many times it doesnt.
With so many users getting the same problem, I really dont think there is some problem with my Xbox. But if it is, I would not mind giving it to the service center.