Mark,

You are getting a lot of good advice, as I knew you would. I would try and 
get the TV down to it's most basic  configuration and see if the problem 
still exists:  Take the DVD, VCR, stereo, or whatever else is involved out 
of the equation.   Just the basic TV getting it's signal from the Dish or 
whatever.   Still have the problem?  You've just eliminated a bunch of 
wires and plugs and connectors and can concentrate  on just getting the TV 
figured out.   If you take the TV down to it's basic setup and the problem 
is gon, restore  the first piece of  equipment, such as the DVD,  and if the 
problem returns,  work on that before adding the next piece of gear.

73, Steve KW3A