This is becoming a big problem for us - does nobody else see this issue? We have 2 linked churches with completely separate OpenLP setups (both Windows 10) and they both do it.
It definitely happens after a video has incorrectly looped back to the start. Videos are not set to loop but nearly always do loop back and replay the first few seconds of the video (the time seems random) before they stop. After this, sometimes the projector output remains black - it seems like the video player window has remained active and is masking the main output.
However, neither the video looping problem or this black screen problem is easy to reproduce. But it is hitting our services nearly every week.