I've run into this on a half-dozen systems that I service for friends. When trying to run the ccsetup558.exe file, there will be an error saying that says, "Error opening file for writing: C:\Program Files\CCleaner\CCleaner64.exe" and choices for Abort, Retry and Ignore.
perhaps ... untick smart cleaning options
ccleaner -> options -> smartcleaning -> untick both
---> "tell me there are junk files to clean"
---> "enable smart cleaning"
Thanks, I'll try that next time. THIS time, I decided to reboot and then delete the C:\Program Files\CCleaner folder. I tried to delete it before rebooting but it wouldn't let me delete a file or two. So as I was going to reboot, I got the message saying that "other people were logged in" and, since CCleaner runs in the background, that's why I couldn't delete the files.
When I rebooted, then deleted the files and folder, I was able to install the new version!
Problem solved!
See second fix here