The computer ran Start-Up Repair upon restart. It ran for over two hours!! (When I hit the Cancel button after 10 minutes, it said the operation cannot be cancelled.)
Anyway, it is up an running now, restored to an earlier date.
The QB link you mentioned refers to earlier versions of QB. I have the 2011 version. I found the following in a link on R11 update search:
[font="Arial Black"]Try renaming your config.msi folder.
Open Windows Explorer (right-click on the Start button and select Explore)
Double-click on the C: drive
Show hidden files and folders (Tools > Folder Options > Select View tab >Hidden files and folders > select Show hidden files and folders > Click Apply and OK)
Show protected operating system files (Tools > Folder Options > Select View tab > Deselect Hide protected operating system files > Click Apply and OK)
Right-click Config.Msi folder and select Rename
Add .old to the end of the filename and press Enter (the folder name should now be Config.Msi.old)
Hide protected operating system files and hidden files and folders again (following Step 3 and 4 above, but hiding, instead of showing)
Now update, repair, uninstallation or installation should complete without error[/font]
However, I am not going to attempt it. I can live without the update.
Somehow, this has also messed up Java. I cannot uninstall it from the Add/Remove window. When I try to, I get the message attached here.
Thank you, once again, for your help. It is much appreciated.