Image malfunction comes with unwelcome superimposed graph lines

I have used Adobe Photoshop successfully for some years now, but suddenly a glitch has appeared. Whenever I open a new file (as in: "File New . . . Blank File," or "File New . . . Image from Clipboard"), it comes with a superimposed grid of graph lines. They look just like graph paper. But I never selected such a feature and would like to get rid of it. Can anybody help me to restore my Adobe Photoshop program back to normal?

Any assistance would be much appreciated!