Hi,
Have you tried to ''reset'' your player?
Here is a link that shows how to do it. Scroll down to find the procedure applicable to your model.
http://kb.sandisk.com/app/answers/detail/a_id/188/~/resetting-a-sansa-player
If that fails to solve your problem, you could try and see if there is a firmware update that you can load into your player to see if that solves your problem.
Be aware that doing a firmware update ''can sometimes erase all of your data ''and it will restore the device to a factory default condition. If you can, copy your data before you try this.
Here is a link that shows you what to do.
http://kb.sandisk.com/app/answers/detail/a_id/278/kw/firmware%20sanza%20fuze