Same occurring to my 160GB classic. Brand new - 1st time I connected to the laptop via usb, I went through the setup wizard, it started synching & then it froze on the apple screen, goes black, then clicks & back to the apple screen again. Loops back and forth. Every so often it says "Charging, please wait..." and then it loops back to the apple screen.
Have tried charging on both my PC and my laptop overnight - same result. Have also had it swapped for a new ipod from the store we bought it & had the same result again! May be a dodgy batch?? a fault in this particular model?