OK,
before the old timers start rolling their eyes, I have searched, and read, the entries on this subject, at least as many as I could. None of them addressed this issue;
this is not really a problem with CCleaner, but, I believe, a problem that CCleaner is locating with certain software, hence I don't expect an answer, just looking for information and ideas.
OK, on running CCleaner Registry Integrity test, I get 2 specific Unused File Extensions entries. The problem is, the files are created by current, valid, and installed commercial software. The programs have not been uninstalled, only occasionally, updated. One of them is a database-type backup file created by one program, but not directly opened by said program. The other one is very similar.
I suspect that the original programmer is to blame for the issue, some flag that should have been set, some registry key that should have been created to register the file type, something... Regardless, the problem remains. I can delete the keys, but once I reboot the problem returns upon subsequent CCleaner scans.
Thanks in advance for any insight or information.