I'm having the same problem as you (I think). My iPod Classic 160 gb got corrupted and I can't put songs on it. I tried resetting the iPod, changing connections, and completely reinstalling iTunes, but nothing has worked yet.
When I plug it into a usb drive on my Laptop (OS: Windows 7) it says "You need to format the disk in drive G: before you can use it. Do you want to format it?" If I click cancel, nothing happens and I can usually go to iTunes. If I click Format disk, a new window appears with many options (Capacity, File system, Allocation unit size, etc.). If I click start (no matter what options I chose), a message appears saying "WARNING: Formatting will erase ALL data on this disk. To format the disk, click OK. To quit, click CANCEL". Sounds scary right? None the less, a message always appears before the formatting can do anything saying "Windows was unable to complete the format."
When ITunes opens, a message appears saying "iTunes has detected an iPod in recovery mode. You must restore the iPod before it can be used with iTunes." I can click "ok" and the click the restore button, but after a while the load fails and it says The iPod "iPod" could not be restored. An unknown error occurred (1439).
This is really irritating! I just want to listen to music on the subway and bus! If anyone has any ideas or tips that would be greatly appreciated.
Thanks