Ipod Classic Frozen, Ok to disconnect

I have a 120gb iPod classic. it keeps getting stuck on "Ok to disconnet" I have tried to reset it, the apple logo appears and it goes back to "Ok to disconnect" When I plug it it to iTunes, it tells me it needs to be restored. I have done this numerous times. I'll restore it put music on it, it'll work for a few weeks, then the error will reappear and I'll have to restore it again! PLEASE HELP