Eu tive um problema semelhante, mas eu tive um alerta informando que a Cortana e minha barra de tarefas haviam falhado. Me deparei com outro site que afirmou para tentar desinstalar o meu software antivírus especificamente Avast. Aparentemente, o Avast e o Windows 10 se chocam. Não tenho certeza se isso é problema seu, mas talvez ajude.
Do those dealing with this problem have avast antivirus installed? If so, I believe that is what is causing the 'critical error'. I uninstalled the software and upon reboot my start button and cortana were working perfectly again. Now I'm sure you all know how to uninstall software on your PCs but it may not work in normal mode with the critical error as it didn't with me. Therefore I uninstalled in safe mode. Incase you arent familiar with how to access safe mode on windows 10, heres how: You press ctrl+alt+delete, and in the bottom right hand corner you click the power button. Before you click 'restart', hold down the shift key until the next screen is displayed (blue). Then click troubleshoot, advanced options, start-up settings, restart. Once it restarts, press the F4 key, and when it restarts you will be in safe mode. Now just do the normal thing to uninstall avast and then reboot following the installation and it should be fixed!
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