Have the same problem, been getting worst

This started a while back, but was only doing it every now and then.
I used to solve it by unplugging the ipod, restarting the ipod by holding the menu and centre button until it restarts and plugging it in again.
This used to work for about a day or two, but it started getting a cracking noise which i assumed was a dodgy wire on the speakers.
It now plays about 15 seconds of song and disconnects.