I purchased a slightly used (floor model) Philips (MX1015) Home Theater system (DVD & A/V receiver) on Monday. On Monday evening everything worked great but last night (for the sake of space), I decided to rearrange my components and moved them to different shelves. After working fine for about 10-15 minutes, the subwoofer started emitting a steady loud signal. When I adjusted the position of the receiver (or entire component cabinent) ever so slightly, the subwoofer functioned properly again. Ten to fifteen minutes later it happened again and repeatedly throughout the evening. The problem happens while in any mode (DVD, TV, etc.). Finally I gave up and turned the sub off. Could this just be a cable problem? I am using an old (cheapo) subwoofer cable. I would certainly appreciate any advice as everything else is working great. Thanks so much.