The update process then stopped and the PC shut down
Since then, Windows boots, gets to the logon screen and after selecting a user, reports "Saving your settings" and shuts down.
I was running AVG Free before all this started. Subsequently I used Sophos and F-prot in an effort to get rid of the initial virut problem
During the cleanup, I also saw hel.exe was in my startup list but couldn't find it anywhere on the system