I'm having the same problem as this guy. No answer was found on his topic, so I hope someone will be able to help.
In my Power Options I have set the screen to
Turn off after 5 minutes and to
never sleep. Closing the lid is also set to
Do Nothing. I also checked the screen saver settings, that the
On resume, display log-on screen might be checked, but it isn't.
I'm guessing it's an issue with the
Turn off the display option?
Extra: I altered my screen to turn off after 1 minute, for sake of testing. As soon as the display turns off and I move the mouse relatively quickly (within 2 seconds), the screen turns on normally, anything later and I need to login again.
Also I am logged in on a AD domain. I'm not sure if this holds certain security settings like this?