I was checking on wikipedia about FFXIII and came across this.
"Freezing and disc read issues have begun surfacing. After initially experiencing the aforementioned in-game "freezing" the game will be rendered unplayable from any save file or even starting a new game. Reports have documented this issue is also potentially damaging video game consoles causing a number of different disc read problems. These vary from only Blu-ray discs to all disc technologies becoming unplayable."
I have it on the PS3 but I haven't played it yet, as I'm currently waiting on getting a PS3 but that's another story.
If anyone has experienced this issue please let everyone else know here.
Check the bottom of the page on this link to see it for yourselves.