Thank you, Akash, for your prompt and helpful e-reply.
From within the article, I clicked the video link and learned to remove the "prefs.psp" file, then restart Photoshop. After doing that, the error message did not appear. And in the Preferences' "Performance" pane now enabled me to see the selection to "Use Graphics Processor" previously, the Graphics Processor Settings section had been grayed out.
Although I don't know what might have caused the processor to become compromised, it appears to be functional again. I trust that it will remain functional for a long time.
Thanks, again, Akash. I gave your comment a "Correct Answer" designation.
Glad to know its working fine now.