I have a Zenith big screen, a few years old, all of a sudden it won't change channels, the picture flashes on and off, ... I have a 3 year old Samsung 1080 DLP that the screen size adjustment is not moving up enough to show the promos that run on the bottom of the screen, also when I do adjust it up as far as it eill go a . read more. Anthony_Infotech. Self Employed. Voional, Technical or ...