It appears, the installer (and uninstaller) is unable to close the monitoring service. After rebooting (CCleaner icon was unresponsive) and closing it manually (System Tray, right-click on CCleaner --> Exit) the installer ran to completion.
LM
Same problem with the slim installer. What is worse, the 5.12 uninstaller hangs as well.
5.13 installer hangs about 5% into the install process. Details window is blank.
5.12 uninstaller hangs about 50% into the uninstall process. Details window is blank.
LM
On my Windows 10 Pro laptop, CCleaner v5.13 installer hangs. Downloaded again, still hangs. So far, I have not detected data loss, but if I do, CCleaner is outta here.
LM