I am using Ubuntu 12.04 in a Dell laptop (L501x), with the 304.88 version of the NVidia driver.
When I connect the laptop to an external monitor the display seems ok. The problem is that every 30 seconds the entire configuration is rearranged. I am getting mixes between laptop-monitor/monitor-only/laptop-only. It is difficult to work with all the windows being refreshed twice per minute.
I read something about adding the following line in the Screen section of the xorg.conf file in a related post Fixing the Nvidia Graphics Screen Flicker Issue (Option "FlatPanelProperties" "Dithering=Disabled") But it did not work.
Any advice would be appreciated. I have no idea of how to configure nvidia-settings to avoid this behavior. I can give more details about output files if necessary.