I am having this same issue. It only occurs when I have dual screen going and allow the computer to go to sleep or lock. Bringing it back up gives green on both screens, and if I unplug and re-plug the monitor(s) in I get a black screen. Logging in is not possible. I have to force a hard reboot to get it working again.
This is NOT a duplicate of 1769383!
I am having this same issue. It only occurs when I have dual screen going and allow the computer to go to sleep or lock. Bringing it back up gives green on both screens, and if I unplug and re-plug the monitor(s) in I get a black screen. Logging in is not possible. I have to force a hard reboot to get it working again.