Also, when running ccleaner, sometimes you need to run the registry scan several times before it can fix everything.
Thanks again for your help. I ran the Malwarebytes, full scan = NO infections of problems found.
Ran CClearner just once (didn't see your last message until I came back to tell you results) It came up with some innocuous-looking stuff, temp internet files and such, and I went ahead with the delete suggestion. Upon reboot, was able to open Add/Remove Programs and it populated readily as it usually does.
As for RAM, 2 GB, and unfortunately, I didn't do the CPU usage check you mentioned until after the other actions were taken, saw nothing out of the ordinary. But, as all looks to be in working order now, so again, whatever was bugged is somehow debugged, and I thank you!