Now..... so far , I've authorized the new one on Adobe, which seems to be the answer, and successfully transferred most of my purchased books via a mix of Reader Library & Calibre .
[I still don't know how to have Calibre as my "default" ereader collection library, rather than Reader, so if anyone knows how, I'd be grateful. I have found that some books I can drag & drop from the "Open containing folder" temp file or folder, but on some original d/loads, than option isn't given, just "copy d/load link" which doesn't do anything helpful....]
However.... my big problem is the PRS now shows "do not disconnect" all the time ! So I can't - well, I haven't had the nerve to yank it out yet !
Is hibernating or even switching off the PC an answer ?