Mark,
If you're running Win 11, right click on your desktop and select "Personalize". Then click "Background" then "Personalize your background" and make sure "Slideshow" isn't selected. If it is select picture or solid color (Not sure if this is even an option in Win 10).
Also, check your Windows power options and make sure "High Performance" is selected. Sometimes mine resets to "Balanced" after updates and this results in stutters with my setup.
Good luck and I hope you get this figured out!!