hey. most likely your roster file has become corrupted. this can happen when you shut off the game in the middle of a save or even during a game. make a change to the roster. move a player from one team to another or mess with the depth chart or something. then go back to the menu and play a game. it should say "saving roster". and that it!
this happens to me a lot because i ctrl-F4 out of the game. easy fix tho.
let me know if it works