You should have received by email several .xtc files showing the problem.
Also an .xtc file with just the four Comments I had in the problem file.
Sorry - not sure how to add filse to the forum yet - need to RTFM !
I see on the XtrxkCAD sourceforge page, under Project Activity, that Martin has fixed the problem.
Presumambly this will be ready to download in due course.
Thanks to you all.