An iPod has been detected, but it could not be identified properly...

I bought a iPod nano 5G a few days ago. I was staying with my girlfriend at the time and decided to sync it with the music on her laptop so I could have a play with it (her laptop runs XP and itunes 9). However when i returned home today and tried to sync the iPod with my computer (Windows 7, itunes 9) i get the following message "An iPod has been detected, but it could not be identified properly. Please disconnect and reconnect the iPod, then try again", under Computer the iPod drive will appear for a few seconds when i connect it but when the message from itunes appears the iPod is ejected.

I've tried a few things but nothing has worked. I have restarted my ipod, restarted my computer, reinstalled itunes, tried every usb socket my computer has and changed the drive letter of my iPod.

I had an iPod nano 4G before this which worked fine, i don't have it with me now to test if it still works but it did a week ago.

Also it probably has nothing to do with it but when i first tried my ipod i had problems with the screen where the light would never turned off. I restored it on my GF computer and worked fine after that.