Black screen on initial boot

Acer laptop running 10 Home fully updated.

Turn the power on and the computer boots very quickly to a very dark black screen. I can just make out the desktop but not clearly enough to do anything. Power off then on again and it boots correctly but very slowly.

Any ideas please?

Try Turn Off Fast Startup, then shutdown and turn on the laptop again. See what it will produce this time.

Thank you, that fixed it.