Thin white static line at top of screen for some channels vizio 42 lcd hdtv

If it's one very thin line (about the width of a pixel) and it's there all the time when the display is on, then you've lost the horizontal driver for that one line of your display. The only repair is to replace the display.

Set the screen format using your TV's menu. Do not set the format of the screen using your provider's receiver. I had this prob with a few channels with a dish provider when I set the format with the remote from the dish provider. I picked up the TV's remote, went into the menu, set the format, problem fixed.

That white line (usually jagged) is actuallly part of the transmitted picture. However, you are not intended to see it because it is located in what is known as the 5% overscan area. Your TVs today are more than just cable ready... they are a versital, technology filled multimedia display. You can see that line because the screen size or wide mode you are using is intended for 1080p/24 signals. You have 0% overscan with this screen size setting. This allows you to see ALL of the picture, including portions of the picture the broadcaster did not intend for you to see. You can change your screen size using the Wide feature in the Setup menu. See pg.62 of your user manual for details and descriptions of the various wide modes.

i have the same problem. any solution

sorry to say you,ll need a new lcd screen
big bucks

Appears most probably to be a fault in the inbuilt power supply capacitors. Getting them changed once solved my problem. If you opt to change yourself then don't blame anyone if it renders your TV unusable!

i solved this by enlarging the picture size through setup, or the V-position.

This is a result of poor conversion of a SD signal on a HD channel.  Go into your settings and adjust the h/v settings to move the line off the screen.  You can do this with a combination of v-position or vsize.  

that is normal, many tv's have this, just change the screen size, does this happen on hd channels too? or only regular channels?

Thin white dashes on top of screen is PERFECTLY NORMAL. It is nothing wrong with the TV, it is the broadcast. What you are seeing is the very bottom of the timecode running. It doesn't happen all of the time or all channels. It usually happens with old 4:3 commercials predating "Digital TV." This is mentioned in your Users Manual. You should be able to adjust the horizontal/vertical position in the menu settings.