synchronize

I use my Sanza Fuse 4gb almost exclusively to listen to audio books.  I did at one time put on a few songs and listend to them, but that has been ages ago and they have since been deleted…  Now, in the middle of a book, I get a pink message that says “Sychronize to continue your music subscription”.  I don’t have a clue what to do with this.  It will not allow me to continue to listen to my audio book.  Just keeps flashing this message.  HELP!!

http://kb.sandisk.com/app/answers/detail/a_id/40/kw/synchronize%20to%20continue

Ah.  Apparently that book had expired.  I had never had one do that before.  I could always take as long as I wanted to listen and then delete.  When I tried the newer book, it works just fine.  Thanks for your help.