VGA is analog, and DVI is digital, so that may be causing the problem. I'm surprised it worked at all, unless you have a converter inbetween that changes the signal.

If you can, try a regular VGA-to-VGA connection, or use a HDMI-to-DVI connection (the sound will have to be routed from the PC to the TV in a specific input. This will require a separate connection) to get the picture you're looking for.