Random voice reading the names of albums and songs appears.

7th Gen Nano: When I'm listening to FM or to music, occasionally a female voice comes on and begins reading off the names of music and albums stored on my iPod. Sometimes I can make it stop by turning off/on, but it makes listening to anything impossible. I tried deleting everything on my iPod and reinstalling the iPod "OS", then reinstalling all music -- but it still keeps happening.

Any ideas?