Now I wonder: Should I purchase a better, beefier Power Supply? Perhaps the PSU I installed was defective new or is just poor quality? I also wonder if it is possible that my Mobo Battery might be shot - but typically those Power Cells are rated for a 7 year life.
I have carefully checked the cables one at a time to make certain they are as they should be. I also spent more time cleaning the unit, getting really picky. But my original problem still exists.
I have the same huge Trinitron (?) CRT that I've used for years. I have a HP All-in-One but presently that is not even hooked up to PC by it's USB. In the past I've used this HP gadget I have along with a VHS deck to put my old tapes to DVD, thousands of them - but I have not done any of that in over a year, and that HP gadget is not hooked up to my PC for quite some time. I use the original Keyboard with a Wireless Mouse. Mouse has been used for some 2 years. I have not added any new software in quite some time, and I do Preventive Maintenance regularly to keep my PC running efficiently.
Sorry for being so chatty but I figure being throrough is better than being glib. I thank you all for your time and consideration and look forward to reading any recommendations you can afford me.