My Panasonic PWD6 is suffering from interference that affects only the top left hand corner of the screen. It takes the form of 30-40 pixels that are constantly flashing black to white. This is not an input problem as it happens on all inputs, including the 'No Signal' blank black screen. This led me to believe it was a mains supply problem, but I have changed sockets, and unplugged all of my 'noisy' household electrics to no avail. Has anyone else experienced this problem?