Elements 2021 preview windows

HI - I've been using Elements 2019 quite happily for a couple of years. Just upgraded to 2021 and have a problem with the preview window. It's lile the image is separated and offset so the video is pink with a green overal offset. I've tried multiple clips which al play fine in other applications but just look bizare in this - see creenhot. I have unistalled and re-installed - still no luck