I discovered that there's PnkBstrA.exe running all the time under Process tab in Windows Task Manager.
After Googling, I confirmed that it is in fact, Punk Buster.
PnkBstrA.exe is listed all the time even BF3 is not running. (checked straight after cold boot)
Why does this process listed even I'm not doing anything related to online game play nor BF3 ? I don't like it - kinda like a spyware..