I'm sorry Igor, in my IM to you I should have explained that I had to use IM because the Beta forum had been locked to us ordinary folks.
Just in case anyone comes by this thread and might just have the same issue the problem application was, in fact, Powerdesk and just turning off the shell extension options in the product was the solution to the problem.
While I regret having raised a false alarm in the forum on that problem it was a bit of a blessing in disguise. It made me go in and clean up all those pesky right click menu extensions that various application believe they must put in by default when you install their product (Izarc, 7zip etc). Generally, the better products do give you the option to turn them off.