We have 3 Directv boxes. On one tv, the picture tiles, but only on the network channels (ABC,CBS,NBC,FOX). The other channels are fine. The other two tv's do not have this problem, so it can't be trees interfering with the signal. I unplugged and replugged the reciever and the signal cable. Directv said maybe it was the multi-switch, but two tv's are working fine. Any ideas out there??
Yes, I did switch the boxes just last night, but no luck. So, I switched the cables on the multi-switch, and that was the problem! Only one of the outputs on the multi-switch was bad. DirecTV technical support was right. Thanks for your help.