8.1 won't boot MUP_FILE_SYSTEM Error

I attempted to reboot my PC running 8.1. I get the error MUP_FILE_SYSTEM reference. I can't find anything logical about this error via google search. I've tried all of the troubleshooting options in Windows except "Reset". I absolutely can't do this. I haven't run a back-up in a couple of weeks and I've been doing major work. I'm desperate for a solution.

Can anyone help? Can I boot past the error through "command prompt"?

Thanks,
Lisa