Reply to KRK Rokit 6's Help

Sometimes when im on my computer and im in firefox, there is some popping or clicking noises (not loud or not to often)

and sometimes my KRK's dont even put sound out when i play music, it will stay quite and the computer will act as if no volume is playing when you open the music icon in the bottom taskbar. any ideas or does this sound familiar to any issues that i can fix?