Yeah I bought it second handed at a legit gaming store but they screwed me over I guess. @Fuk, do you mean all the patches they offer?
Whenever you start your game, it should say, you need to download version 1.06 or whatever. You need an internet connection to do it.
Some copies are just unfortunately filled with more glitches then we would like. But the game works clean for me. What console you got it on?