I updated my computer last night to Windows 10, and went to bed while it updated. I woke up and it was stuck on the black loading screen that says Dell in a circle with the rotating white dots in a circle underneath. The dots are frozen as well. Doing Ctrl+Alt-Del doesn't do anything. I can turn it off with the power button and when it turns on it goes back to the loading screen and freezes again. How do I fix this?