I have a Lenovo X140e Thinkpad (originally had Windows 8.1, now had Win10) that has a peculiar shut down problem. Whenever I have it plugged in it shuts down just fine, but not when unplugged. When unplugged it goes to the windows "Shutting Down" screen with load wheel, then the screen shuts off, however the hardware keeps running (power on light, wifi on light and fan are clear indicators). Does anyone have a clue as to what might be happening? Would it be an OS-related problem or would it be BIOS related?