it's not a setting particular to your keyboard, it's you timers for putting devices into low power states (dim or turn off your screen, when to go into standby/sleep/hibernation, etc.).

It was a similar problem with XI too. Almost like Windows isn't aware of any input from you if you aren't using mouse/kbd... like it isn't tracking all of the players input or something. So, after windows thinks you've been inactive long enough, it starts putting things in a low power state.

Before putting everything on my laptop in an "always on" sort of configuration, I'd get the black screen after about 30 minutes of solo play...but when chatting up with friends it never happened. Now I can solo for hours with no screen blanking.