Chameleon "crack" ruins the game?!

Hi,
i played the game with my cds for a while now, until I saw there was a "crack" available. (=> http://m0004.gamecopyworld.com/games/pc_chameleon.shtml )

I applied the files and the game starts normal, but I got some random crashes, graphical & gameplay issues (weapon won't reload )

I reinstalled the game and used my original discs - and had no problems at all

So my problems have to be linked to the russian unprotected files i think..