sansa clip 4gb is recognized, but never completes syncing

I have had a few on and off problems with my sansa clip 4gb–I was getting an error message after a while sometimes that the usb device was unable to be recognized.  this happened off and on, and was fine after I restarted my computer (I’m on windows vista).  Now, I’m trying to sync it to windows media player again, and it recognizes it, and then says it it synchronizing, but never finishes.  The screen on the sansa clip just continues to say “Reading”.  I did put it into the hold position, press the center button, and plug it in, and that worked, but it was recognized as a completely different device and I’m not sure I want to go through and move some stuff around because I updated playlists and everything.  Thanks for any and all help!