Over the past few weeks I have noticed some picture glitches while watching sky. I cannot pin it down to any particular channel and it happens during live viewing and recorded programs. They are black lines that are a few pixels in width and differing lengths that appear for only milliseconds, probably just one frame. I keep seeing these a few times a day. When I rewind live tv the error is still there and I have managed to pause it at the right time, see attached pictures. Anyone have any ideas?