08-02-2015 05:24 AM
T420, no docking station, with external monitor connected to VGA port. Windows 8.1 64-bit. Display driver up-to-date, Windows 8.1 up-to-date. Lenovo Syetm Update run and everything is up-to-date.
So occasionally it switches back to single display (laptop screen) then immediately switches back to dual display. Seems to do this randonly without warning.
I don't see any obvious issues, event log does not show any problems when the issue occurs.
I did reinstall the display driver but that did not help.
This is more of an annoyance then anything else. I just stop what I am doing and wait for it to switch back to dual display, as I use the external monitor as my primary desktop.