update 3 - well for anyone waiting with bated breath for the final outcome...
i had to delete notes.db. luckily I ony had a few books iwith notes, not a few hundred, as they all share that one file.
it was in a state where if I added any other book by same author as the original problem book, then any attempt to create a note in that book would crash the reader.
could not live with that so I zapped the books.db file from windows.
I guess the only other fix would have been restore to factory default ( assuming that i Could find instructions for that somewhere [aka hard reset])
poor systems design to use a single database file if it is easily corruptible