I also have this problem, on a Dell M3800 with factory-installed Ubuntu 14.04. I've had it for a while but never connected an external monitor before. External monitor = Dell E248, connected via Mini DP with Mini DP to DVI adapter.
I also have this problem, on a Dell M3800 with factory-installed Ubuntu 14.04. I've had it for a while but never connected an external monitor before. External monitor = Dell E248, connected via Mini DP with Mini DP to DVI adapter.