Full explanation and steps to fix are here:
http://www.pcgamesn.com/how-to-turn-off-gamedvr-windows-10
If you don't want to make an account then follow the steps to edit the registry. I've done this and all is now well.
http://www.pcgamesn.com/how-to-turn-off-gamedvr-windows-10
If you don't want to make an account then follow the steps to edit the registry. I've done this and all is now well.