Okay, I have just bought oblivion (a preowned game, but in v. good condition), and played it for about 40 mins before recieving an error message saying the disc is unreadable. I have tried cleaning the disc, but it doesn't work. Is my hard drive broken? Is there anything I can do without getting my Xbox repaired, and if this is the only option how can I do this and what does it cost. I live in the UK.