I have uninstalled the CCleaner and reinstalled it several times in the admin account. In my theory the installation of the Trial-Version is the solution, because the trial does not allow CCleaner to manage all users. Once it is installed and running the entering of the license key a change to all users is uncritical.
But suddenly I have again the same issues and have noticed that CCleaner cannot stand a temporary change of the Windows-User-Account from Standard-User to Admin back.
Latest issue: Smart Cleaning is not cleaning cookies at all, but manually “Custom Clean” is doing it. But “Smart Cleaning” should do exactly what “Custom Clean” is performing. Maybe I start a separate thread for that. I am using CCleaner since 2012 but I am a little bit exhausted of a software which is paid and causing so much dysfunctional trouble.