Thanks, for the explanations, but I still need a better fix (work-around) than I've found. (P.S. Nergal, I Did NOT put CCleaner in the 32bit Program Files, it did wind up there!)
I have McAfee AV, I can't find any version when brought up, and it's updated automagically. I don't think that AV is the cause.. Even if it was, that's moot at this point.
If you go back to my first post - the first time It didn't work I found that my 64 bit version being called while installed in the "PROGRAM FILES" directory.. no idea how the previous install got there. Let's just put that aside, and work on why it continues to NOT WORK --
I uninstalled it from that wrong directory, had to delete the CCleaner directory as re-install wanted to keep going back to the 32bit directory. I created CCleaner subdirectory in "PROGRAM FILES (x86)" and custom reinstalled (forced) it there. Didn't help. CCleaner64.exe runs after the install but subsequent running it shows that it starts, but immediately stops.
But now I'd discovered that running the 32bit CCleaner.exe first (& it too fails),, BUT THEN the 64bit CCleaner64.exe NOW runs!! (all done from the directory itself, not from the desktop)... Other clue was that the uninstall from 'program files' left the directory there, and a reinstall would go back to it!!?
Was hoping this 'clue' would help explain what I should look for in the registry or wherever to get the proper fix... There's something obviously bolloxed up in my system.