Basically: Installed CCleaner > After the setup is complete, I checked the "Run CCleaner" box so I can use it already > Used it > Closed it.
After that, everytime I try to open it (double clicking the icon) nothing happens.
I tried unchecking the "Automatically check for updates for CCleaner" and launching it in Safe mode, still no success. Seems to me like the only way I can use CCleaner is installing it over and over again.
Don't use the same installer over and over. To eliminate installer corruption as a cause, uninstall what you have, reboot, then download and install the slim build from here.