I had the same problem and switched to the Monster HTS1000 and that did the trick. I did not even have to connect the amp or any of my other devices to the monster, only the cable connection. I returned the 1000 though because I actually wanted to connect my equipment and got the 2000 off ebay for $105. You can try the monster buy buying it at circuit city,best but, or goodguys where you can take it back and get some better of ebay or used. I also tried the mondial magic, but upon installation it did nothing for that system and reading the instructions states that it is only for properly grounded cable systems.
Patrick
Patrick