Are you using NVIDIA driver with TwinView?
My config after reboot the computer is still OK.
grep UScreen ~/.xsession-errors
UScreen: Screen geometry changed:
UScreen: #0: ? 1680x1050 +1280+0
UScreen: #1: ? 1280x1024 +0+0
UScreen: No primary monitor has been configured via Xrandr.
UScreen: Primary monitor is #0 according to GDK and confirmed by TwinViewXineramaInfoOrder.
UScreen: Primary monitor for Unity is #0.
dpkg -l | grep unity | grep vv
ii libunity-core-4.0-4 4.24.0-0ubuntu2b1vv3 Core library for the Unity interface.
ii unity 4.24.0-0ubuntu2b1vv3 Interface designed for efficiency of space and interaction.
ii unity-common 4.24.0-0ubuntu2b1vv3 Common files for the Unity interface.
ii unity-services 4.24.0-0ubuntu2b1vv3 Services for the Unity interface
Are you using NVIDIA driver with TwinView?
My config after reboot the computer is still OK.
grep UScreen ~/.xsession-errors aInfoOrder.
UScreen: Screen geometry changed:
UScreen: #0: ? 1680x1050 +1280+0
UScreen: #1: ? 1280x1024 +0+0
UScreen: No primary monitor has been configured via Xrandr.
UScreen: Primary monitor is #0 according to GDK and confirmed by TwinViewXineram
UScreen: Primary monitor for Unity is #0.
dpkg -l | grep unity | grep vv 0ubuntu2b1vv3 Core library for the Unity interface. 0ubuntu2b1vv3 Interface designed for efficiency of space and interaction. 0ubuntu2b1vv3 Common files for the Unity interface. 0ubuntu2b1vv3 Services for the Unity interface
ii libunity-core-4.0-4 4.24.0-
ii unity 4.24.0-
ii unity-common 4.24.0-
ii unity-services 4.24.0-