Error upgrading to iPod Touch 3.0

I try to update an ipod touch to the last software version (3.0), iTunes ask me for the payment, i filled the requested data and the software was downloaded by iTunes, meanwhile the ipod was connected to the pc. When the software download was complete, iTunes says that the iPod is preparing to be updated, the iPod show an image with an usb data cable and an iTunes icon, after that i get an error message saying that an error was detected and the update process is stoped. The iPod still shows the usb data cable and an iTunes icon, i restore it to fix this issue but i cannot update the software. Three times i attemp to upgrade and the three times i get an error message.

What can i do?...