Punkbuster, oh the troubles I have seen. Are you using Vista or XP?
I could tell a real long story of my problems with punkbuster but here is the short version starting with the ending.
Conclusion, Punkbuster on my system runs fine under XP which is the only reason I'm running dual boot.
Punkbuster under Vista is a nightmare. Launch a game Lan or single player no problem. Launch the same game and play online. Punkbuster starts up 1 or 2 additional processes in addition to the one which is always in the background. It begins it's aggressive disc scanning. Available physical ram takes a progressive nosedive. After all the physical ram is gone the computer starts paging more and more resulting in game lag until the video driver crashes. The only common variable in this has been Punkbuster.