I set a restore point (useless gesture) turned off my anti virus (McAfee) and pressed down lightly on the update button. When it was all over I got an error message and an apology. The 2004 version was installed but with problems. Windows promised to try again later. Took me five restarts to get things working, sort of. Worse, each time I restarted a Malwarebytes pop up claimed they had just blocked a piece of ransomware.
At length I realized Malwarebytes was the culprit. I uninstalled Malwarebytes, shut down and then rebooted. My desktop is now working just fine. I’m not going any further on my own. I’m going to wait until Windows decides to patch up my installation.