Signal strength on my Toshiba 42HL67 seems to be varying wildly, resulting in brief pixellation of the picture every couple of minutes. The TV's signal strength meter normally bounces around between 65 and 80 (on a scale of 100), which is fine, but every two or three minutes it goes down to 4 or 5 for a few seconds. I live in Alexandria, just 5 - 10 miles from broadcasters in Washington DC. My antenna is in the attic. I recently moved the TV from one antenna outlet in the house to another; I did not notice the problem with the old outlet. The new outlet has a much longer cable run - ca. 60 feet longer than the old. I have wondered if the cable might be broken at the new outlet, but since it works 95% of the time fine, I don't see how a broken wire could be the cause.

Any suggestions? Thanks.