How do i fix my punkbuster error in COD 4?

ok i jus got cod 4 on my pc but i used a torrent so yes its cracked and i play on cracked servers (plz no comments about buying the game i had my reasons for doin it this way) now everytime i open the multiplayer game i get an error saying "unable to initialize punkbuster punkbuster disabled" so i go on the option 2 re-enable it but when ever i get a good server it kicks me like mid game for no reason nd it does it constantly...can anyone tell me what i can do to stop this from happening?