Locate the pbsvc.exe file in your Downloads and run it again, always as an Administrator.It's merely a rule of thumb, but don't be lazy and just do it Once it has finished, restart your Computer in order to free its memory from any trace of PunkBuster.Then click the Compatibility tab and check the box that says "Run this program as an administrator" then click the OK button". To do that, right-click your mouse on the PBSVC icon and choose Properties from the pop-up menu. Under Windows Vista, you also have to tell Windows that you want to run this specific program as an Administrator. That means you have to log in as an Administrator user before running PBSVC. "Since PBSVC is installing a system-wide service, it needs to be running with Administrator rights during the installation process. You can find a copy of the old FAQ page here. Quoted from which unfortunately has been revamped so the following paragraph is no longer there. If you don't see the "Run as administrator" option, you can find other ways on this page į.A.Q.: Why do I have to run it as an administrator? Show/Hide Spoiler Run it as an Administrator, choose "Un-Install/Remove PunkBuster Service" and click "Next".Download the pbsvc.exe tool, directly from (backup here).If you are being kicked with an error message regarding PnkBstrA.exe or PnkBstrB.exe, " This PB Server Requires (A1393 C2.306) - Error loading pbag", " No Packet Flow", and (sometimes manually updating helps with the Losing Key Packets 9005 / Service Communication Failure as well), start from here: Step 1) Reinstall the PunkBuster Services
It is the most complete and successful way I could find, but more techniques are listed at the bottom, under "Other ways to update it".
Then, try to manually update PunkBuster (as it does not officially support BF2 anymore), with the following method. First, consider searching your error message in this thread: List of PunkBuster errors.