I have an aftermarket video system (DVD Player w/ Alpine headrest monitors) installed in my '05 Nissan. On occassion, I get a loud intermittent buzzing sound (sounds like the kids game "Operation") from the front right speaker. The aftermarket compoents are not directly connected to the Bose system - i.e., no FM modulator, etc. Could this be a ground / power problem? Appreciate any suggestions on how to troubleshoot or fix this. Note: the buzzing is not affected by the power on / off status of the Bose system, DVD player, or monitors.