LG 32LC7D Television "rgb pc vista working" Questions

RGB(PC) port I am recieving the invalid format messag when I try to hook my PC up to the TV. It was working fine. I'm still using the same cable. When I first turn my computer on you can see it on the

...RGB input as it's called on the TV.) I use a VGA video adapter on the mini DVI output port, then use either 1024x768, 800x600, or 640x480 resolution (the only ones supported by the TV--others will ...

RGB-PC cable. I did nothing to set this up, it simply worked the first time I tried it. The quality has been excellent and what would happen was on the RGB-PC channel on the tv it would say "no signal