Macbook Pro - iTunes

I listen to the radio on iTunes but lately it seems to jump to the next station on it's own, if I click back onto the original station then it plays again for a few minutes and jumps again, if I leave it on then after a while it will jump to the next one again and so on, the internet is still connected.

I've tried looking on the Apple website but I can never find an answer - it's doing my head in!!!

HELP

Thanks