windows 10 freezing quite often

I got my computer with windows 10 in April this year, yet it has been freezing up at least 20 times. It never freezes up while I am using it, but always happens while I am away. When I come back, the power button is on, while screen gets no signal. My mouse wouldn't work either.

It says about "Stop Code: Memory management," after I force-shut down the computer. Can anyone help me? Thanks