We have the same problem. Not only does the treadmill mess with the picture, but also portable electric heaters. My computer tech thinks it's a voltage drop problem and suggested buying a good quality battery backup unit used for computers. The better ones have line conditioning & filters built in. I haven't tried it yet. I was hoping that AT&T would get their act together first and improve their box, before I have to invest a $150 to make their substandard equipment work.