Hi Brian, thanks for reporting this crash. I think I've got a fix, I've sent you a test build.

re:
> So I guess my question is, where is the documentation of how to create and do a construction line.

The construction line docs are here:
https://moi3d.com/4.0/docs/moi_command_reference11.htm#constructionlines


> Where is the latest construction line script. (mine looks like 2009 version?)

I think there are links here:
http://kyticka.webzdarma.cz/3d/moi/#KeepCLine

Thanks,
- Michael