I am having a great deal of difficulty with user accounts: 1. Settings>Accounts>Sign-in Options goes absolutely nowhere.

2. Control Panel>User Accounts>Manage your credentials returns the following error.
Error code: 0x80070425
Error message: The service cannot accept control messages at this time.

3. Trying to reinstall from Media Creation Tool returns the following message.
Error code: 0x800704dd - 0x90016
There doesn't seem to be any problems running anything else.