[GeoffR]

Another thing to check, if you are running an automated backup prograqm on the computer that you plug your reader into, make sure it is not storing anything on the reader.

Also, do you add new covers for your books in Calibre? I do this, I find most books have cover images that are far too small/low resolution, so I add a bigger/higher resolution ones to Calibre from the publisher's website. But beware that for some books, if Calibre can locate an existing cover image in the book, it will replace it with the new cover as it sends the book to the reader. Because of this the size of the epub file on the reader can be much larger than the size in Calibre. (The size reported in Calibre doesn't include the separate cover image)