For some reason my dad is unable to read any books (including books previously read) on his Sony PRS-350. They are coming up as DRM restricted - this has only happened in the last few months and he read the books well before then. He hasn't downloaded any new books in over 6 months. I've tried connecting, ejecting and disconnecting as well as hitting the reset button but nothing has changed. There are no books in the library on the reader library. Any help would be very grateful!!!! Although please bear in mind that I am not very knowledgeable in the tech department!