Found a potential fix from the Steam Forum.
"!SOLVED!
In my case, a simple trick worked. It was not reinstalling the game (got the same problem afterwards) but as I reinstalled PunkBuster (the original one from the BFBC2 folder). To do that, just go to the file where BFBC2 is installed, search for a folder called instal, go into and search for a file called punkbuster. there should be the original PBinstal.exe (or something like that). just start it and select "repair/reinstal". It should work, after you finished testing succesful (in other case, repeat that procedure). Have fun playing! (For those who didnt understand: this video explains exactly what I mean:"
Heres the link...