My IPod keeps turning itself off

Does anyone else have this problem? I'll be listening to a song & it will just shut down. I don't have any alarms set, & I can't find anything about this in the manual, but it's really getting on my nerves. Also, the battery icon in the upper right hand corner doesn't seem to have anything to do with the one that appears in the middle of the screen. The one in the upper right always appears to be fully charged, but I have run out of power when it looks likt this. The large one that appears in the middle of the screen seems to show the correct amount of power, but I can't figure out how to make it appear.