I have Ubuntu 12.04 64-bit installed on a Dell E6500 laptop, most of the time in docking station, with external Dell 21" display.
When installing additional drivers for the nVidia graphics card the only screen available is the internal laptop screen. There are no means to get the external display working.
The "System Settings --> Displays" only shows the laptop internal screen.
But Unity can work in 3D mode. (/usr/lib/nux/unity_sopport_test -p)
When removing the nVidia drivers, the two screens are nicely detected and are working as they should. When closing the lid of the laptop only the external screen works when opening the lid both screens turn on and when removing the laptop from the docking station the internal display switches on, but Unity only works in 2D mode.
Has somebody seen a similar problem and found a solution?