CCleaner starts and just when the green bar gets to the right end of its travel, ccleaner just disappears. The window disappears. I tried 5.40 and it's the same result.
Using windows 10
This has been reported as happening when Windows 10 is in safe mode without networking. (Boot option 4).
It seems to be OK in safe mode if networking is enabled. (Boot option 5).
There have also been reports that the same happens with Windows 7 in safe mode.
https://forum.piriform.com/topic/52111-ccleaner-crashing-in-windows-safe-mode/