Lock Screen Appears And Programs Shut Down After Extended Idle Time

[g-unit1111]

So I'm having this problem where I leave my system on for an extended period of time, and when I come back to work / play on it, I get the lock screen and all my applications that I had open are now closed. I have scoured through the menu options and turned off nearly all the power saving features as this is a desktop (my Dark Knight rig) but I can't find the feature that is needed to turn off the lock screen. Does anybody know where this is?

 

[inanition02]

What operating system? The latest versions of Windows like to update/restart themselves when idle...