Same happened here Hugo, but after it had downloaded itself a screen came up with accept or decline what it had done. I clicked decline and it told me that it would take me back to where I was. i.e. Windows 7, but it may take some time. Right I thought, ......you mucked it up.... you can sort it. I left it and it got rid of it and I am now back where I was......................for now till it does it again.