My Dell XPS 8700 loses use of its USB keyboard and mouse after updating to Windows 8.1 from Windows 8.
The update mostly seemed to go OK, but after using it a while and then shutting down or restarting, Windows starts to the splash screen showing the time and date, but it doesn't respond to my USB keyboard or mouse. There is no mouse cursor.
As a result, I can't clear the splash screen to log in. My keyboard works fine, for example to do a Bios setup. I can't seem to be able to boot to Windows safe mode. What can I do?