98 4dr accord subwoofer starts to bang

Greetings, I have the following components on my 98 4 dr Accord: This is what I have installed so far:     * Alpine CDA-9886     * Boston Acoustics SX60     * JL Audio A Series A4300     * JL Audio CS112RG-W1v2 Every now and then, suddenly, the subwoofer goes crazy and starts playing really loud. I can hardly play anything, so need turn the system off. Next time, when I am in the car, the system plays perfectly. About to be two years old. Any basis error that I am ignoring? Thanks for your help!!

With the system playing, and someone in the car to turn it off if the problem arises during this process. Can you duplicate the noise by hitting the top of the amp with your fist? If you grab and move the RCA cables at the amplifier, does it make the noise then? Next time it is making the noise, try removing the RCA jacks and see if it quits.