Hello people thanks for your inputs. I have just gone back to W10 from W11. That surprise, surprise, made no difference. Looking elsewhere, I have come to the conclusion that the graphics card is not well. As said before the PC can stay on for hours with no load. Start the sim and after 3-5 minutes the PC crashes. The temperatures do read normal, about 60 C, however the upper surface of the graphics card are extremely hot. Event viewer and appcrash tell me nothing. I am coming to the conclusion that the card is becoming faulty.