If it is the TV, start weeding out issues that the TV may have.
Check all outlets that EVERY piece of gear is connected to with a inspector quality tester.
Even if everything checks, get some thick grounded ext. cords and plug the set into another outlet on another circuit.
12/3 is good, 10/3 is better.
Put all sources on the same circuit if they are not already, even if this means running multiple heavy extension cable across the room.
10/3 directly from the panel's convenience outlet with all other breakers shut off would be the final test as far as power issues in the house...
(you may have to reset some clocks, but be sure to shut down your computers and DVRs first)
Disconnect all coax feeds, surge protectors, etc. and try a single source (plugged into the same cord) with audio and video feed only.
If it still happens, and that DVD player is OK on another TV in that house, your set is likely bad or you have something weird about your power delivery from the grid to your panel.
You will have to call the utlility company to get a clean bill on health on that one.
You just bypassed the wiring in the home, so something else is to blame.
You will need to do that test, because this is the #1 utility company excuse, "it's probably the wiring in your home..." NOPE, GET OUT HERE.
There was a guy that worked for us that had a Seleco HD-250 dual mode that freaked out at his place, and it worked fine anywhere else we took it. That specific processor in that specific projector on that specific AC service was the problem.