Black horizontal lines

This was a product malfunction with that TV. Dell ended up paying out $$ in a class action suit over this product...I think I got a check for like $30 in the end. There is no fix I was told...but try to toggle the master switch, or unplug and plug in again - that often times worked for me. In the end I bought a new tv though because the frustration level was too much.

Firstly i would suggest you to perform Self-Test Feature Check (STFC)
Your LCD TV when used as a computer display through DVI and/or VGA connection provides a self-test feature that allows you to check whether your LCD TV is functioning properly. If your LCD TV and computer are properly connected but the LCD TV screen remains dark, run the LCD TV self-test by performing the following steps:

1. Turn off both your computer and the LCD TV.
2. Unplug the video cable from the back of the computer. To ensure proper Self-Test operation, remove both Digital(white connector) and the Analog(blue connector) cables from the back of computer.
3. Turn on the LCD TV.
4. The floating 'Dell - self-test Feature Check' dialog box should appear on-screen (against a black background) if the LCD TV cannot sense a video signal and is working correctly. While in self-test mode, the power LED remains green and the self-test pattern will scroll through the screen continually

This box also appears during normal system operation if the video cable becomes disconnected or damaged.
Turn off your LCD TV and reconnect the video cable; then turn on both your computer and the LCD TV.If your LCD TV screen remains blank after you use the previous procedure, check your video controller and computer system; your LCD TV is functioning properly.

OSD Warning Messages

A warning message may appear on the screen indicating that the LCD TV is out of sync range.
See Specifications for the Horizontal and Vertical frequency ranges addressable by this LCD TV. Recommended mode is 1280x 768 @ 60Hz.

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http://support.dell.com/support/edocs/monitors/w3000/en/Trouble/TROUBLE.HTM

Here is one for $10 plus shipping, click on the link below to view:

http://cgi.ebay.com/Dell-W3000-HD-LCD-Flat-Panel-TV-Remote-A215-P-n-M3011-/260720518882?pt=LH_DefaultDomain_0&hash=item3cb42766e2

Yes I tried it and now I have nothing, not even a green light. So much for that. I have 2 of these sets. If you never unplug them from 110 I never have a problem. Un plug them and wait 2-3 days and nothing.
Any lawyers what to take this on?

I BOUGHT A NEW TV.

This may not be DVI issue.
I connected DVD player HDMI ----> DVI ( Dell W3000) LCD TV.
Later I found that Dell TV version of DVI does not support HDCP protocol ( High Definition Content Protection protocol). So I could not play HDMI to DVI movies from my DVD player instead I use Y Pb Pr -- this works ok.

Hope this helps... I am not use PS3 enforces HDCP - I assume Sony linked with Sony Pictures would enforce HDCP on HDMI cable.

Try turning the master power on and off a few times. Give it a few secs inbetween power offs and that should work. It's worked for me. Sometimes it takes longer that other times to show a picture.

Yes, I believe it is a power supply issue.... Problem is, I can't locate one

It's repairable, sounds like the main board, but try some other cables and sources to see if the same thing happens