This error generally occurs due to a dirty or scratched disc. Try the following:
- Take the disc out, ensure there are no scratches or defects. If the disc is scratched take it to a retailer to get it resurfaced - If the disc is dirty, wipe it down with a dry, lint free cloth or a piece of clothing (be very careful the clothing is 100% cotton. Do not rub the disc hard or it will scratch)