Do you use the EVGA precision overlay? that will cause this issue... Just about any overlay that shows your framrate or temps on screen will cause this problem... I was getting the same error, stopped the overlay, restarted the game, no more PB errors...
Might be some program in the background causing this, try turning off un-needed programs in the system tray. If that doesn't work then update drivers for Graphics Card and Sound Card.
Common programs causing this:
ATi Tray Tools
you should right - click on the game in steam. Then click properties, then deselect the enable steam community in game. The steam overlay can cause punkbuster problems. This is how i stopped that error.