Thanks for your reply and sorry for mixing up the questions.
Yes, i have divided my 3rd screen into 3 areas and i use topper & DMD during the game but successfully used the lower part, apron for the regular VP DMD, when game is started.
This have worked fine for me the last 18 months an it looked good.
After upgrade to 4k screen and new PC, it worked for a short while, then I upgraded to 5.37 and even installed a paralell Core version for test but I had the same problem.
I can also see that the video I use in the topper stops playing when I start the game, that wasn't the case before my upgrades.