Interesting Ravi, so the interference cannot travel via the antenna since it is not connected in your house. I would not think that DVD players put out a strong enough signal to travel 50 metres through the air and be picked up via another antenna.
If it goes via the AC lines as you say there is a simple cure, fit ferrite toroid cores round the cable, like the ones you see on the cables of computers and switching power supplies.
Another thing you can try is to fit a more directional antenna to your TV set, as long as the station transmitter is not in exactly the same direction as your neighbour :? .
You could also ask your local antenna installer to do some field strength measurements with his instrument tuned to the DVD output signal, just to see how strong a signal comes out of these.
Good luck
Klaus