Hope this helps.
I'm now merging everything into a new scene.
- Found a forestpack distribution of a corona light (sphere) that coused realy slow performance. That could be the problem (if so; I've fixed it).
- I can already exclude all the railclone objects.
- I can already merge everything except for 9 forest pack objects. Save the file and open it without problems.
My best guess is that the problem was aither the forest pack lights, or one of the 9 remaining objects. Thay also have effects, so I think that might cause some problems.
I'll try to import 4. If they don't have the problem, then it must be the 5 others. etc till I find the problem Forest pack.
The dificuty is that I can import everything. But when I save and open, it crashes the new imported scene.
I hope you can see something in the dump files.