Problem here too with win 7 laptop and win 10 desktop. After reaading the posts here, this is what I did. I deleted/unpinned all shortcuts to ccleaner. I then made a new shortcut on the desktop pointing to ccleaner 64. I pinned it to the start up and taskbar. They all worked, launching normally. I did a restart (not a cold boot) and they still worked.
This is probably unrelated but, I have avast and one of the options in the troubleshooting is to have avast load AFTER all other services, in other words, no boot scan on start up.
I did a fresh (cold) boot this morning and everything still works. Ccleaner launched normally.
So, I can't really say what fixed it, but I suspect it was the shortcut . So far so good.
Off topic, but still looking for a good free AV. They are all so bloated now.
Odd that everything worked perfectly before version 5.10