Thank you for the explicit reply which did work once I connected to the web.
I had since deleted everything WA I could find and so had to add serial number again and that sorted it ALMOST. Bad luck the error box was not a little more informative (two underlying popups show no content at that stage).
Now same happened again after registering and closing connection and dreamweaver, seems I have to connect to the web EVERY TIME I want to use DW and add / edit an HTMLEditor.
That is unsatisfactory as I don't trust any software that has to converse with a website WITHOUT my expressed permission or knowledge. Nor do I trust the continued paranoia checks AFTER registration and I realize that that policy probably has nothing to do with the tech staff.
Go back 15+ years, and I have always only connected to the web when / as needed (by me) and I watch out for idle time data transfers too; that level of paranoia is acceptable from the PC point of view but not from a products point of view.
So after all that, thanks again but I don't think the HTMLEditor is suitable (wish I knew before buying the licence).