Well, lol...Both copies are now working !
I copied across the whole directory to the new windows install, which solved the activation issue...
While on the original I downloaded old updates until at 7.4 it started to work
http://files.thegamecreators.com/darkbasicprofessional/upgrade/dbpro_upgrade_7_62.zip had to manually alter the _62, to find archived updates.
well, at least I can compile all my old sources

And not resort to a new language (for now)
Many thanks to all who helped and sorry for my rant :-|
I still have no idea why later updates no longer work on the original windows, but think it must be due to some other program interfering in some way....
I uninstalled AVG anti-virus, but no luck there, in safe mode DBPro seemed to want to work, but complained about graphics modes
But, at least some progress has been made and things work to some degree....