This happens to us about one day in three when trying to record the news, and the EPG timer seems to be confused, often putting both in - or removing both when trying to delete one.
Panasonic support were initially helpful, but are off the radar now. They suggested all the 'digital data' wasn't being received regardless of whether picture/sound was OK and to buy a VHF/UHF splitter. This made no difference.
Also, when deleting a recording the Confirm Delete dialog box has 3 blue rectangles areas that look like they should contain text. Ours don't, they're blank. This again, we were told, indicates a poor signal.
Location here is Mosgiel. We've a yagi type outdoor aerial and a masthead amplifier.