"I have to switch it off at the back, unplug from the mains, wait until the static had gone then turn on again"

Why do you have to do all that? Just press the power on button and keep it pressed. Your computer should turn off,and you can reboot it. No harm will be done, and there's no question of having to wait until static has gone - I'm not sure why you think that.

Your computer shouldn't present you with a black screen when there has been an update, although finding out why it does so could be involved. An easier workaround would be to alter the settings so that it doesn't download and install the updates automatically. Just click on 'Start' and select 'Control Panel', then click on 'Windows Updates' and select an alternative setting. See how that works, and come back to your thread if you need further help.