According to a few people on the internet, Final Fantasy XIII has been freezing on both PlayStation 3 and Xbox 360. I personally have yet to have any issues with the game on my 60GB launch PlayStation 3.

It seems to be isolated cases (from the amount of comments and posts I have seen, no one other then those linked on the posts are having problems.

But if you are having a problem, get in contact with Sony or Microsoft as it would likely be your hardware that is playing up if you have tried other copies of the game and it is still faulty.