It seems that the crashing Lightwave does is a well known problem.  I have upgraded to version 9, with free LWCAD, and when I try to add plugins in modeler Lightwave goes in the huff. It turns out that it has been an ongoing problem and the culprit is LWCAD. Well, if that’s what I have to suffer to use the excellent LWCAD then I suppose that’s what I’ll have to suffer. I hope they fix it for 9.5. But, seeing as, according to the forums, it’s been happening for a few years, I don’t expect they’ll get round to it.