Here's how to get the game to work :
1- You need to download razor's new fixed crack .
Download it here : http://www.rockgamers.com/gtaivcrack.html
2-Page might ask you to download a toolbar , Just download it like I did . It won't take you more than 30 secs anyway .
3- Extract the rar file and you should get 3 files .. launchGTAIV , GTA IV , 1911.dll .
4- Copy all the three files to your GTA IV installation directory .
5- Launch the game and have fun :)