Double line when watching dvd's-please help

Hi I have been getting a double black line (which is only visible against a light background)when watching dvd's. I have adjusted the round focus dial on the front of my projector, the sharpness control on both my projector and dvd player, but it doesn't make any difference. What could be causing this? Is there anything else I can adjust or do to correct this? Thanks!!
I have seen a similar artifact in a friends CRT set up. This was a very thin line running from the bottom of the screen to the top of the screen slowly. It turned out to be a ground loop problem. It seems this is the video equilivant to the hum we hear in the audio portion when cable tv boxes are not properly grounded. Just a thought, hope this helps.
Ground Loop, yes. It's either cable being of different ground differential or it's from having different grounds from components(possibly due to differnt circuits for your gear/video stuff. Anothe cause could be if you're using a different power source for some of your compoents(I.e., PS Audio powerplants and power generators for some, then using straight into the wall for others. I think if you plug all your stuff into one circuit to check(including video display and gear) you should see problem go away. Good luck
Hi I posted this thread and think I was misunderstood. It is not a line from the top of the screen to the bottom. I see a thin black shadow line around any and all objects (people, trees, anything in the movie) I notice it with dark objects against a lighter background. I am using a Richard Gray power conditioner. Thanks.
Another long shot. If your display device has a circut called a SCAN VELOCITY MODULATOR (in it's menu) turn it off. It can lead to excessive edge enhancement (outlining) and possibly the double line you are seeing. Why not contact a ISF calibration service and see if they can help.