Emerson AV301 Home theater Amplifier POP

I've enjoyed the affordable luxury of surround sound and surprisingly rich music reproduction for almost two years through an Emerson AV301. Lately, the unit will POP it appears, through all speakers simultaneously and at random intervals ranging from 30 seconds to 30 minutes. After several POPs in rapid succession it sounds as though the speakers will smoke and be permanently silent... then it may be hours until the next POP. Any idea, or similar experience? Thanks for the consideration.