So each core, or processing unit, in a chip usually has a table that maps the virtual addresses used by individual programs to the actual addresses of data stored in main memory. (sciencedaily.com)
This error may also occur if you attempt to remove a book from main memory by deleting the *. (wiki.mobileread.com)
It is ridiculously easy to copy books to your SD Card or the devices main memory and then import them into the reader app. (goodereader.com)