How can I restore my ipod nano 3g? (completely)

I've tried using the standard iTunes restore option, but I always get a error message saying that it could not be restored and that 'an unknown error occurred' (1439). When I select more information, and I try the sugguestions there- nothing worked. On the windows side of things, (win 7), it always asks me if I want to format the drive, because otherwise, I won't be able to use it. When I tell it to format the ipod- I get a windows message saying that it was unable to do it.

Also, when i connect the ipod, sometimes i can see it in itunes/the computer- but then it disconnects and reconnects and disconnects......over and over. I've tried using different USB ports- no sucess. I tried using the disk mode also- but the only advantage with that is that it stayed connected long enough for itunes to recognize it and notice it is corrupted, and needs to be restored- but then I'm at the beginning again.........

Please help...!