Hello,
I have an Acer 771G notebook and when I installed debian wheezy, I had my external monitor plugged. Now, if I restart my computer with the external monitor plugged, gdm3 shows ok and I can use the computer normally. However, if I start the computer without the external monitor, the notebook monitor turns off until I plug the external one. I tried to turn the laptop the default monitor, but no success, when I restart the computer, same thing happens.
Any hint on how to solve this?