Since the unexpected settings appeared before the config was restored, and were still there after it was restored, my guess is that whatever has happened is unrelated to the backup/restore process, and either config changes are not sticking or there's some confusion about which settings have which effects.
To test if the config changes are sticking, what happens if you change some of those things back to how you had them before, then reboot the machine? Do they revert back again, or do they stick?
If configuration changes are not surviving a reboot, it's likely your user profile folder where the Opus config is stored (type /dopusdata into the location field to find the location) has been permissioned to deny your own account write access, or that all the files & folders have had their read-only, hidden, or system attributes set (or a combination).
Also, did you load any config backups from anyone else? e.g. Some tutorials and "themes" (which aren't really themes) come with them, and they will replace the whole config if used.
The corrupted lister format persists through a reboot.
The backup and restore was of configuration from Dopus on this system.
The corruption seemed to result from doing a search for content within a structure of files, then closing the search window and results window. (By the way, the search interface is very poor and counter intuitive. Perhaps there are settings to change the interface.)
I can not find options to restore my fairly simple configuration - pretty much the default configuration.
So the only option really is to uninstall, reinstall, and then tailor the toolsbars, etc. Not fun at all.
I did an uninstall and reinstall. The following problems require solution:
The second row of the lister toolbar contains "Lister" and four icons on the right hand side: dual horizontal, dual vertical, metadata pane, viewer pane. How do I obtain explorer and commander style icons? Is there no way to view a single file list in explorer format?
The lister contains three vertical areas: folder tree, second panel listing files and subdirectories for the current directory, third panel listing files and subdirectories for the current directory.
How do I configure the right panel to include its own folder tree?
The Explorer style only has one file display (and a folder tree) so I am not sure what you mean by "single file list", unless the style has been customized from its defaults (which shouldn't be the case if you just did an uninstall & reinstall, unless you have changed the config or imported a config backup, etc.).
Turn on Preferences / Folder Tree / Options / Open second Folder Tree in dual display mode. You may also have to update the default lister (via Settings > Set As Default Lister), styles, layouts, etc. if you use them and they only open one tree.