A gay ass peice of shit anti-hacking game software. If you do not know a lot about computers or you have vista, chances are if you get a game which has punkbuster enabled for multiplayer, itll give you many errors. yes punkbuster does prevent hacks and most people do not get kicked from it, but its possible that you fall into the small category of people being kicked by punkbuster daily, for no reason at all.
Anti-Cheat software from Even Balance that should prevent people from cheating in the games it is integrated with. Possible source of nuisance because of no backward compatibility, and many updates every once in a while.
See wallhack
When you go play Quake3, and you just started getting on fire, and suddenly you're "forced to spectator mode until PB version updates", you know what time it is.