Thanks Male_M3dia - I guessed that was the issue. It still leaves the issue of how to save Scene elements, made up of Genesis, for easy re-use... which is a major part of my workflow at least.

However... after some more playing around last night, I managed to delete everything apart from my Genesis figures from the scene, at frame 1.

Then I cut the scene down to just the 11 frames. Then saved that as a Scene file, to the new Poser Scene library.

Then I imported that scene back into my new reconstructed scene, in which I had removed / baked in the single piece of cloth dynamics that required the original 30 frames.

So far, have managed to work a bit more on that new reconstructed scene without it crashing.

Fingers crossed.

There are definitely improvements in build 1.0.0.27, in terms of performance. At least, for now, I've got back to having a use-able scene... and it does have everything in it... which is a pretty reasonable amount of content, no denying that!