Thanks for your prompt reply.
I tried Tom’s script. It still crashes. As you wrote above, I think the project has something corrupt at a level that is not accessible to the editor. I will start a new fresh project and see what happens. If it still crashes, I will ask Tom about it.
[Edit: I think I found my problem. I was trying to import the positions by going File>Import then selecting a .T3D file I had pasted the script results into. Edit>Paste works just fine. I hope this helps someone.]