Sounds like a subwoofer. They are suppose to be sheilded, so I don't know why it'd mess up your TV and all. I have a monitor sitting on top of my 10" sub without a problem.
Why not just remove all your speakers(that "box" and the other smaller speakers) and see if that clears things up. You can buy decent sets of speakers for cheap. Maybe you could find one with a sub that's actually sheilded.
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Desktop * Athlon X2 4200 | 2G RAM | 160G HD | 7600GT
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