The other night at the exact moment when I unplugged the mouse (USB) of my PC running Windows 7 Home Edition, the computer shut down instantly. It started back up fine and there were no problems. Is this normal? Does Windows 7 require a mouse?
This is not normal. Windows 7 will work without a mouse. Also you should be able to unplug USB devices on a running machine. It sounds to me like some electrical spike or short circuit occurred and the power just shut down. This would mean that either your mainboard or power supply is not working properly any more.