Re my query, above, I read per a response to Tigerlily's "error message" to run SFC. This brought up SETUPX.DLL as corrupt. Not knowing if it was the original or an update, I clicked on the first option instead of the second "replace with original", ran SFC again and got an (apparently) clean report - no faults.
I would still appreciate a reply. Now to close down and start up a few times.