John, when you send files to a card rather then using the BookPort software to send them some of the necessary control files which BookPort needs to define phrases and the like are not available to it, even though in music, phrases aren't the way of navigating. The BookPort software has to be used. Curtis Delzer On Fri, 24 Sep 2004 19:48:50 -0400, john kolwick wrote: Hello group, I recently transferred a number of music mp3 files onto a flash card and wanted to play them in my bookport. When I attempted to play the files, the bookport said mp3 error. I transferred the files from my PC to a flashcard drive, would that make a difference? Thanks for any assistance.