Radio Interference - HELP

I have a Toshiba 30HF84 high definition tube tv. I get diagonal lines across the screen on the high def stations. It only occurs when the dvd is plugged into the tv. I had the comcast people out here several times, the tv repair twice, and finally the dealer brought out another one. It still does it. I have a am radio tower a couple mile away. I orginally had my old Toshiba dvd hooked up through component video. Then I bought a Denon 2910 and hooked it up with HDMI. Same effect, maybe a bit stronger. I am using a Monster power filter. I don't have room for anything larger than a power bar. My question is what to do? 1. Get a new power bar? 2. Have the electric company install a power filter, 3. try a different tv. Note: when I moved in I had problems with the telephone reception upstair, as I could hear the radio station.
2 things you might try - first confirm the source of the problem . Is it the DVD player ? what happens when you disconnect the power cord on the player? I doubt it is the actual connector (eg component or HDMI) If this goes away you may have a ground loop- these are elusive. One suggestion is to try a ground loop isolator on your coax cable at the point it comes from the wall - you need to break the ground- a power filter will do nothing in this regard- it may be that your cable leads in are not properly grounded. A ground loop isolator should be something Comcast could provide - I'd also ask them to ensure their cable is grounded ( and therefore not acting as a big AM antenna). If not them then through a good stereo or electronics store.
The second route is to contact the relevant telecommunications authority re the AM station - this would be the FCC I believe in the USA. There are rules on how much interference they can generate.
It does sound thought that something in your house is acting as an antenna,
You mght also want to google "solving ground loop problems" Hope that helps - I had a similar problem. Cheers.
A friend of mine had this problem when he bought a new treadmill. When he turned on the treadmill, he got lines on his tv. We found in this case that his coax was too close to his power cord behind the tv and the RF was being transmitted to the coax. The treadmill was in a different room. This may not be true in your case, but I would isolate every cord as much as possible before I spend the big bucks. Good luck!
Could likely be that the player is radiating RF energy (hi-freq clock) back out of its' AC cord. Clamp an Audioquest RF Stopper on the AC cord as close the the component as possible. Perhaps another on the TV's AC cord. RF Stoppers are detachable ferrite ring filters & they come in two sizes, so check which diameter best fits your cabling. I think I've heard that Radio Shack also sells ferrite rings.
I went back to Comcast after isolating as much as possible, including a Radio Shack ferrite ring. I plugged everything into a Richard Gray 600. None of these made any difference. I called Comcast and they told me that I can only use RCAs (white, yellow and red) out of a dvd, when I have their HD digital box hooked up by component video (which as far as I know is the only choice). They told me that using either an HDMI or component cables out of the dvd will produce interference with the HD signal. I asked why their service people, who came to my house on 4 occasions, never told me this before. The response was "sorry." Is this also true with satellite?
Tlday....WTF did they tell you this with a straight face? I dont get how they cant fix such a big problem
After trying two identical Toshibas, I replaced with a Sony. Problem gone. Go figure. Comcast remains on my bad list, however.