kc1di and semicolon:
Figured out how to take "second step" after F9 to kill Caja, which was indeed the CPU hog!
Now, temperature back to normal low 40's C degrees. Caja was stuck in some kind of process loop, because I was definitely not using or launching.
And yes, now that I have killed, I cannot launch Caja from menu and will need to reboot, reload or reinstall.
But, this issue is separate from the other and if cannot be solved, will pose the question in forum. However, you can certainly suggest a good retrieval method for Caja File Browser if you have a few seconds.
Sincere thanks to all.