Jody is having an issue of an annoying hissing sound when he's streaming video through his Roku. Leo says that he thinks it's a decoding error in the Roku. Try using another Roku device and see if the noise is replicated. He can also try different sound settings, but it sounds like that 5-year-old Roku just needs to be replaced.
Patrick's computer fell off the desk onto the floor. Now it makes a loud sound when he boots it up. Leo says to turn it off right away. He should make sure he eliminates static electricity and then open it up the case and inspect the fans. Chances are, one of those fans was dislodged and it's getting in the way of the fan blade of the computer. That could short circuit the PC.
John just bought a powered subwoofer for his home theater and when he plugs it in, it makes a humming noise. Leo says that's called a "ground loop" and there's ways to fix that. The plug isn't properly grounded, or could be loose. Or the stereo itself is causing it. John should go to RadioShack and get a magnetic ferrite coil that snaps onto the wire. That will eliminate it. If it doesn't, then an electrician may need to check his wiring and power.