Problems with no cd crack in windows vista

[Treufiction]

Hello

I got a problem with windows vista when i try to no cd crack a game.
I downloaded manhunt and installed it, but when i replaced the original .exe with the crack and started the game windows vista gave me a message that the .exe didn`t work anymore.
When i do the exact same thing in windows xp it works perfecly and i can play.
Is this some sort of new security feature of windows vista or something?
Can somebody help me please?

grtz