Admin local account has 'lost' Start from Task Manager > Processes > Background processes. This is what we did see, before this error appeared. Does anyone know how to reinstate Start within Task Manager? 

Our other local accounts do not have this error, so only the Admin Local account attributes have changed, but do not know how to reinstate Start within Task Manager. (Do not want to create another Admin local account.) 

Now, when in Admin local account, clicking on Start Menu (Windows) does not open and creates critical error window saying "Your Start Menu isn't working" and Windows 10 does not fix this error. The appearance of this window that we cannot dismiss, is an unwanted nuisance.