Intermittant vertical black bars on 42HP84

you need to change the 'zoom' on the tv by the remote.
Normal mode frames the 4:3 video to the 16:9 picture area by displaying it in its original aspect ratio, with vertical gray or black bars on both sides of the screen. The disadvantage of this method is the fact that the image is small by virtue of not using the entire width of the screen. This is also known as the 4:3 mode.
Full mode Full mode horizontally stretches the 4:3 video evenly across the entire width of the screen. This is the proper mode to display anamorphic video. If used for standard aspect ratio video, everything on the screen will appear wider than normal. Contrast this with anamorphic video displayed without processing on a 4:3 display, in which people on the screen will appear taller than normal. This is also known as the 16:9 mode.
Zoom mode Zoom mode evenly stretches the picture both horizontally and vertically, until the picture fills the entire width of the screen. This crops out the top and bottom of the picture. This mode is used for letterboxed and open matte video.
14:9 mode Main article: 14:9
In 14:9 mode, the picture is magnified more than in Normal mode, but less than in Zoom mode, while retaining the original aspect ratio.
Wide Zoom mode Wide Zoom mode, also called Just mode, Horizon, or Smart Stretch, progressively stretches the picture horizontally, less in the middle and more on the edges. This allows normal aspect ratio video to be displayed across the entire width of the screen, with minimal cropping, and with much less of the unpleasing visual stretching effect of Full mode.

Two possibilities are there. The first one is, with loose LVDS cable, that connects the T'Con board to display panel. The second is the fault with its main digital processor board.
http://electronicshelponline.blogspot.com/

You can test the memory sticks with memtest86+
http://www.memtest.org/

If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Line faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

Y sus board issues

see that it may be from the resolutions..if you give it a smaller one ..and it is a wide screen format ...it will hae black 2 inches wide band on each side... just right click on desktop properties and settings ..and restore a normal resolution on it ..

Sounds as if screen is going out..

Go to Control Panel
Accessibility Options
Screen (should be third tab)

Move Width bar towards "Thinner".

This works if you set the system cursor; your wordprocessing program might have another setting, usually under "Options", "Preferences" or "Setup".

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Depending on the location, it could be the Logic Main Board, or a buffer board