I have a file with problems. I used “save as” to save a copy of the file for rendering (with raytraced viewport mode). I then did “extract render mesh” and deleted the NURBS in the new file, added a ground plane from the library and tried to switch to “raytraced” -> crash. When I re-opened the file it was empty - but not only that - also the original NURBS-file was empty, when I opened it!
I had a copy of the original file on my laptop (and Time Capsule). I made a new ‘save as-copy’, extracted the render mesh and deleted the NURBS-objects in this file. Now the files are ok - except for the fact that the ‘render-file’ always crashes, when I switch to “raytraced”…
I sent the crash report and the file to McNeel (forgot to zip - sorry about that).
Edit: The original NURBS-file doesn’t crash when switching to “raytraced”, so it’s something with the materials I guess.