I have seen similar to his back to 2010 but never found a real answer.
We need to project a slide with a very short video of fireworks unto the backdrop at a local theatre. The Projector is high up on a light bar
2/ ALL slides have a black background so they do not show up on the backdrop
3/ We start the show with a black background slide and manually pull up a lens cover in front of the projector = works fine
4/ Spacebar brings up the next slide which has a 10 second video/sound clip = works fine
5/ Spacebar to the next black slide though causes a WHITE rectangle to flash up = Not good!
Presently the only recourse is to lower our manual shutter before the transition.
We have tried increasing the options total memory and memory per slide etc.
This is a shame because we like OpenOffice and use it for everything else - and we do contribute.
Any thoughts appreciated.
We have another gripe but put it in a separate thread