Ipod playing through speakers and headphones?

Hello,
i have one of the video ipods. 5th generation i think, not to sure though. when i play it it will play both out of the ipod its self and the headphones attached, and when i try to put on the radio it says that the headphones aren't connected, even though they are connected to the ipod fully. i have tried different headphones, just in case it was a fault of the headphones, and yes i have resetted it almost 5 times now, and no improvement. it is still under warrenty so if noone has any suggestions and nothing can be done then i'll have to send it away, but i would like to try to get it done as soon as. thankyou.