-Unistalled and Installed Cod4
-Updated Pb
-Removed Anti-virus
-No firewalls blocking it
-Tried even this http://www.cod4boards.com/forum/showthread.php?22189-Fix-Punkbuster-Service-Communication-Failure
-Also I follow ceeee's steps
Do you have any other games installed that use punkbuster if yes uninstall them and update PB http://www.evenbalance.com/index.php?page=support.php PBUpdate and direct it your folder where its installed