I'm sorry to hear that you're having this issue.
The television is replicating the picture exactly as the picture is being sent.
What I'd recommend is edit the name of the input you're using after you switch the resolution to a supported PC resolution.
MENU > INPUT > EDIT NAME > PC (or applicable selection) > [Enter}
Does that help?
When I connect my computer thru HDMI the screen has 1" black bars on the sides of the tv. In the picture settings menu the "Screen" option is not available (greyed out - why?). The best I can do is switch to wide mode, but that stretches the screen way too far on the sides. Any owners or knowledgeable people know how I can access the "Screen" menu to stretch the image, or find some way to stretch the image to fill the sides flush?
--the 40" model if it matters