Power conditioner needed????

I'll vote for a cable induced issue. Most troublesome audio and frequently video anomolies are the result of the cable or satellite grounding.

Simply go out to the power pole where the cable or sat is grounded and lift (disconnect) it temporarily. Wait about 30 mins and look at the picture. it may taek a few more mins but in an hour or so you should know if that is the issue.

it's a simple enough task/test. If it is the issue there are isolation transformers that can solve the problem very cheaply.

True too you might not have a good enough ground. Sandy soil sheds water quickly too. Arid areas can be issues. I've heard from more than one source simply watering the ground rod area can remedy things.... which might account for the late night no prob thingy you have going on there.

If in an apt. simply remove the coax feeding the sat/cable box. Wait a while like i SAID ABOVE AND CHECK IT OUT.

Battery chargers too can cause problems in an audio or video rig if in close ckt proximity to the gear. timers too, like on hot water heaters, dishwashers, and or lighting.

If it is a ground loop, a power filter/conditioner usually isn't the fix.

you can also try using a decent sized ext cord and plug the TV into another ckt altogether.

Dew point raises at night, and your situation eases then, and why I say I feel it is a ground oriented issue. Unless you and your neighbor are using the same service I doubt the neighbor is the problem.

Good luck

Thanks for the responses. There are no dimmers in use. Good suggestion though............I forgot all about that one. I did not even think to disconnect the sat. system. I assumed since there is distortion even when I am only using the DVD player, that eliminates the sat. TV. I suppose if it is a grounding problem it will be there as long as the sat. cables are connected. Since this is a weekend lake house, I will have to wait a few days to give that one a try.
The dry ground rod theory is interesting since the ground rods are under a covered deck. Hmmmm...that could even be a safety issue. Dang. Just dang.

For not all that much you can get a Monster or APC unit designed for home theater with dedicated outlets offering component specific filtration. It makes a big difference and for a few hundred bux its less expensive then many alternatives.

FWIW I have always found that video displays benefit the most from power conditioning.

You could also try upgrading the cables from the sources to the display or the receiver and then to the dispaly - I doubt that it will fix the problem but it might make a nice small difference once you do...

What happens with the raster when there's NO input connected at all? (this could be a way to trace the interfering source).

If you have any GFI (Ground Fault Interrupt) distribution panel breakers or GFI outlets in the house, they too might be a problematic source of your RFI (radio frequency interference). Flourescent or halogen plasma lighting can even be an issue, but apparently not in your case

At one point, the only breaker that was still on was the one for the TV.

Regarding possible differences of ground potential on your incoming RF coax: you can try grounding the shield connector by stripping a few inches of small conductor (#22 awg or so) insulated wire & wrapping that around the F-connector shield, fastening it with a cable tie or tape wrapped around. Then connect the other bared end to an AC outlet cover mounting screw, which typically ties electrically to the AC outlet's ground. Or you can go right inside the outlet box & pick up the AC ground connection directly.
I've had to use this shield grounding technique for video hum bar problems; others have used it successfully too. Your situation seems a little different, but this is simple & easy to try.
You can also try completely isolating the coax by connecting two antenna matching baluns directly back to back (available at Radio Shack). The incoming coax connects into balun #1, then the 300 ohm twinleads tie directly to each of balun #2 twinleads. The 75 ohm isolated coaxial output is then taken out of balun #2. This is inexpensive & introduces some small signal losses, but if you have signal to spare then it's not a problem. There's a $100 coaxial isolation box available (from MIT?) that may or may not(?) introduce smaller RF losses. Sorry I don't remember those specs or the brand for sure.

There could even be a source of external RFI getting into your equipment (nearby radio station transmitting tower or cell phone tower). Or a neighbor's CB radio or Amateur Radio transmissions. That might need to be shielded or trapped out. You can try a product from Audioquest called RF Stoppers. Basically they are split ferrite rings that come apart & snap together around your cabling (RF &/or power cables, etc). There are two levels: the Juniors & the Regulars, which are twice as thick & yield more RF filtering attenuation. Various diameters (I think?) are available. I saw a similar product at Radio Shack years ago; might still have them too.

AC line conditioning is also worth trying of course. If the power cord is a detachable IEC type, some upgrade AC cords even have built-in filtering (such as JPS, MIT, or Custom Power Cord Co.) and many others. These cords have sometimes been reported to significantly improve video quality, even where interference is not an issue. Search the forum archives for specific posts in that regard.

Thanks Bob! You lost me at "balun", but I understood most of your advice. I am going to start with removing the sat. box and DVD player altogether. If all is well, I will add back in the DVD and go from there. I am also going to check the neighborhood for Amateur Radio antennas. I am going to try watering the ground rods as well. (under cover of darkness, of course)
And then there is the nuclear power plant only five miles away.......