device stopped regonizing files!

I bought the sansa clip to listen to audio books.  I download the audiobooks from my library with the use of overdrive media console that was recommended and was happily listening to them until just now, and I cannot seem to get any of the mp3 files or the wma files to work.  they appear to be on the device when I scoll through the directory on the sansa clip, but when I checked to see if they were there on my computer, they would not pull up in the windows files or in Rhapsody.  Please help!  I bought it from best buy less than a month ago.  It forced me to sign up for rhapsody to activate all the features of the clip.  Could this be the problem?    Please help me!

Message Edited by srothaicp on 02-22-2009 06:19 PM

have you tried formating it then re syncing the files back on to the clip

if this does not help do you have it on the right USB mode.