This happens all the time. The cause is usually noise from a digital source contaminating the rest of your system. I don't know what kind of tuner you have, but you're options are to get a higher quality tuner, a PC like the JPS Digital AC, or a power conditioner that isolates the outlets from each other.
If you call Cable Company and explain your problem, they'll know what to send you (demos that you can try first to make sure a product fixes the problem).
If you call Cable Company and explain your problem, they'll know what to send you (demos that you can try first to make sure a product fixes the problem).