I know the answer to this problem! Or at least the most likely answer.
I have had the EXACT same problem described by GarVanNeath. I even took the disc to be cleaned, used another persons copy and still nothing worked!
It turned out (for me at least) that the game can't seem to run correctly with too many saved players.
One possible reason for this is that if you delete or edit a player after you start a tournament, it still seems to look for the EXACT version of the player, which no longer exists!
Also roster changes and squad management alterations seem to do the same thing!
I found once I started my squads from scratch and wiped my created players, (yes, it was a REAL *****!!!) the error no longer came up.
I'm not sure of any specific reason for this error message, but I do know I'm on the right track.
I tried EVERYTHING, I even tried tranferring the roster and profile files to another mates X-BOX, only to have the same error. Even with TWO copies of the game!
I'm sure of isolated the above problem as being the major cause of repeated crashes on X-BOX.
Hope this helps, and applies to your situation, GarVanNeath.