Hi Nukecad, Thanks for your reply! It has NOT always acted like this. It used to always be available in my System Tray (your "overflow box'). And, I would occasionally get a pop-up message telling me that I could save xxGB of space by running CCleaner. I have not seen one of those pop-ups in several months.
And, if I run it manually and then close it, it stays resident and is available in my System Tray. See attached screen clips. CCleaner is there because I ran it manually about 3 hours ago and it will remain available there until I restart my PC. I am beginning to have doubts that it even runs at startup.
Oh, one other thing that I JUST now noticed - when CCleaner comes to the front, it disables Greenshot (my screenshot utility)! In the 2nd attached screen clip, I had to use the Windows Winkey+Shift+S to get the screen clip.
Thanks for your help!