For some reason many people have trouble after installing Call of Duty 4 from Steam in Vista systems. PunkBuster refuses to install correctly and when trying to join a multiplayer game you will get the message “Error Initializing Punkbuster” and, as a result, you will be kicked out of servers.
Although I found some answers by googling most of them were not very clear, so I decided to write what I hope is an easy to follow guide to fix this problem.
1. Move the pbgame.htm, pbsetup.exe and eula.txt files from wherever you created your Steam install folder. In my case it’s at “C:ValveSteamSteamAppscommoncall of duty 4PB”. I created a folder under this called “old”. It’s not strictly necessary but you always want to keep backups just in case.
2. Download pbsetup.zip from http://evenbalance.com/index.php?page=pbsetup.php
3. Extract the file pbsetup.exe from the zip into your Steam install folder.
4. I ran pbsvc.exe to uninstall the service and then again to reinstall it. Not sure if that’s necessary, though, but I did it anyway.
5. Run the pbsetup.exe you extracted from the downloaded file.
6. Add your game (it should now be listed), and then click on “Check for Updates”
7. Updates should download now and after a couple of minutes your can play your game.
That’s it! You will be able to join multiplayer servers now.