thanks
It does seem to be related to “rendering” somehow.
When it goes “mad” and I jump frame by frame, i get a green frame, a black frame , a normal picture frame and then repeat.
I did throw out everything in the render folder, to start fresh.
problem persists though.
The only new filter involved here is a NEAT, grain reducer.
these problems seem to have come, some time after applying this, but hard to be sure.
i have used this filter many times before, with no problem.