In attempting to connect my laptop to my TV using the VGA output to the RGB input, I accidentally it up to display only on the external monitor. This wouldn't be a problem, but the image on the TV is garbled and unusable. I would like to turn this off, but I have no options to do so unless the computer is connected to an external monitor (in which case I cannot make sense of the output). Interestingly enough, this does not happen when I connect to a second TV with a DVI input. However, the settings I apply there do not carry over to the RGB TV. Is there anything I can do to turn this off so that I can continue troubleshooting my external monitor?