If all else fails, reinstalling cod 4 should definitely fix it
no
Close cod4 . turn off your router for a min or so and turn it back on.. All should be fixed
and no
Dark must shut down his computer and restart it that will fix it (and dont let his computer goes in sleep mode as he does)
his punkbuster is running twice
Or
ctrl+alt+delete and stop all hiw punkbuster process (what I did with teamviewer few days ago)