I actually have the same problem. I was using it normally and then i decided to do a restore cause windows was accusing some dumb problem, but it was actually fully fuctional, just took a while to appear on itunes. After the restore it appears immediately on itunes...and it locks itself as soon as I turn it on. It's clearly not a hardware problem as I was using it just before restore. There's a thread on apple's forum describing this problem exactly and 53 people hit the "me too" button. It never got solved. I don't know what to do either. But to me it seems like some bizarre bug that never got fixed.