Help! iPhone won't play songs! :-(

I think my iPhone is punishing me for considering going with another phone...

When I go into the iPod app and select a song to play, it looks like it is starting to play it but then after a fraction of a second the screen just rotates back to the song list! Sometimes it skips to the next song also for a fraction of a second but then still goes back to the song list!

Does anyone have any suggestions? I tried turning it off and on again

Martin