"Reinstall CCkeaner and when installing leave the 'Run CCleaner' box ticked in the last screen of the installer so that it will open from the installer." The idea is good, and I have checked it out. Unfortunately it is not the solution, even not after uninstalling and clean reinstall.
It is obvious that the issue has something to do with permissions, because when I change the account from local user to local admin CCleaner is working on that (former local user) account properly, inclusive CCleaner icon in the system tray (thank you for correction).
I have attached five screenshots with the permissions of ccleaner64.exe in the local user account (hope the German text is understandable). Any ideas which permission is missing?