Thanks for the question. If you have not already done so, does resetting the iPod nano help the issue?
If not, it may be appropriate to restore your iPod:
Hi Matt, thankyou for your advice re my ipod. I have another problem....I copy audio disc books into itunes and then onto my ipod. Theres no problem if I copy them into music on the ipod but if I copy them into books, all the discs are out of order...i.e scrambled. Can you suggest anything? Cheers, Rosica