Sometimes, I would press the power button to turn my screen off, and then I would return to my SP3 and turn it back on to continue to work. It works just fine most of the time. However, once in a while, but still too often, I turn the screen off this way, and when I come back, I can't make the screen turn back on. I didn't even leave my computer alone that long. I can still turn on the backlights for my Type Cover keyboard keys, which means that the SP3 is definitely still on. But for some reason, I screen stays black, no matter how many times I press the power button, something on the keyboard, or the mouse buttons. I have to force shut down my SP3 by holding the power button until it's completely off, and then afterwards it works just fine. But whatever I was working on will be gone. What exactly is causing this, and how do I prevent it? Help, anyone?