I found a thin black line near the bottom of my TV today. What can I do to disappear that line?

Timing control board.

Try adjusting the aspect ratio. However do have in mind that some movies will still have black bands at the top and bottom of the screen.
If the aspect ratio on nearly every setting has no effect you will have a fault on the TV.

That is done through the remote.

If by "nasty wide horizontal lines" you mean LETTERBOX masks (at the top and bottom of the screen), all you need to do is select the correct ASPECT RATIO for the program you are watching. Consult your USER MANUAL to determine the menu settings for ASPECT RATIO.
If you do not understand what "aspect ratio" means, or what different aspect ratios exist, do an Internet search for "aspect ratio" and read.

CHANGING THE SCREEN ASPECT RATIO: ( From Manual )
The TV can display images in four different modes: Wide, Zoom, Panoramic, and Normal. Each mode displays the picture differently. To change the screen aspect ratio:
1. Press the MENU button on the remote.
2. Use the Arrow buttons to highlight the Wide icon. Press OK.
3. Use the Arrow buttons to highlight your desired screen mode and press OK:
• Normal preserves the content's original aspect ratio. Since the 4:3 aspect ratio is not large enough to fill the TV's screen, black bars are added to the left and right of the display image.
• Wide stretches a 4:3 aspect ratio picture to the edges of the screen. Since the picture is being stretched, the display image may appear distorted. If the program is already formatted for widescreen viewing (1.85:1 or 2.35:1), then black bars will appear on the top and bottom of the display image.
• Zoom expands images with black bars to fit the screen.
• Panoramic expands the display image to fill the screen.
images may appear wider than intended.
If you are watching widescreen (1.85:1 or 2.35:1) content, black bars will still appear on the top and bottom of the display image. This option is only available when the TV is displaying a 480i/480p source.

This may be a video driver problem if it is present in all source materials. I would press the menu button on the set or remote to get the internal display generator working then if the line is still there you either need to call for a warranty repair or if out of warranty this needs to be checked by a Technician. It might just be a bad connection on a ribbon cable or it may be a failure in the display driver circuit. This is why I only buy Sony products but the problem can happen to any company as they all use the same display type circuits- a attribute of the "better" flat panel displays.

The people look fat and stubby is due to trying to display pictures that were made for old TV 4:3 aspect ratio and you are now trying to fill in the TV screen that has 16:9 aspect ratio. The only way for you to see proper pictures is to set the aspect ratio to 4:3 mode or set it to automatic to let the TV select correct aspect ratio of the pictures, the bad part is that you will see black bars on the left and on the right of the pictures, see more details with regarding to the aspect ratio in the user manual.
Learn more here also:
http://hometheater.about.com/od/televisionbasics/a/aahdtvfaqs6a.htm

http://reviews.cnet.com/16:9-widescreen-tv-aspect-ratio/

Not sure about your sound problem.

It's bad.

This is an aspect ratio issue. On the remote there is a button for changing the ratio to either 16:9 or 3:4. I think it depends with ones remote control but the button has a square as its label. Try looking for it or refer to the user manual. That would be my first guess.

Problem is solved. I unplugged my DVR from my receiver for about a minute, reconnected it, and the that solved the problem.