I have this problem off-and-on, as well. It is a highly annoying, easily fixed issue for a software giant... I love everything else about the device. I found a way to mitigate this without simply keeping the screen on always.
I first went to Control Panel > Hardware and Sound > Power Options > Edit Plan Options, and set the device to sleep after _______________ (insert preferred time here)
I then went to Control Panel > Appearance and Personalization > Personalization, then clicked Screen Saver Settings, then set it to Blank > Wait ______ minutes (insert preferred time here, the less the better to save battery. I chose 1 minute)
This isn't a straight-up fix, but darned close.