Thanks for the information
I've also discovered that sony did a update on the reader software about the time that the problems started However I have since discovered that if I download any books from kobo (epub format) they download to the revised sony reader and I can transfer them to my device. Likewise I can down load any books from my public library without problems.
It seems that my sony software has authorised any drm content for transmission to my prs 300.
But the adobe ADE2 is still displaying that it is unauthorised to copy content to my prs 300
I think I will leave it as is for now and await further developments