I have found a suggestion on the web to stop the Host Task problem, but it did not restore my start menu / taskbar issues. It had four suggestions but this was the explanation for the solution below:
After the recent 1709 update by Windows, many system functions began conflicting and numerous problems arose. One of these problems is the one we are discussing. There is a workaround present for users experiencing this problem post-1709 update.
Press Windows + S to launch the search bar. Type “account” in the dialogue box. Open the first relevant result which comes forth.
Once in the account settings, navigate to “Sign-in options” and uncheck (turn off) the option “Use my sign-in info to automatically finish setting up my device after an update or restart”.