Ipod Nano Problem

[lola jax]

I have an 8gb Ipod Nano and it has suddenly come up with a message on the screen saying the following...

Firewire connections are not supported. To transfer songs, connect the USB cable provided.
Press centre to dismiss.

However when I do press centre the message temporally goes then comes back. Also it won't let me turn it off now, when I hold down the off button nothing happens.