Yes, something is very wrong. Can be malware, can be some corruption.

I'd try your spare admin account first (always make 2 admin accounts when setting up Windows!). If you don't have one, see if you can still make one from Config Panel or with the net user command from command prompt, or - if it doesn't work from the command prompt - from the repair options on the recovery drive you made (always a recovery drive!) or from the repair options on the Windows 10 install disk or stick you can make (that's free from the Media Creation Tool).

If no luck with a new user it's time to go back to your latest image or your recovery drive or to factory conditions or to reset or refresh Windows from that disk or stick you made with the Media Creation tool.

Yep, managing Windows can be quite complex.