I use VirtualBox 4.12 with Ubuntu 12.04, and up until a couple of days ago I was able to sync my iPod nano, my iPod Classic and my iPad via Windows XP and iTunes.
A few days ago, when I connected the iPod nano, iTunes told me it was in recovery and I'd have to Restore it. I did this, but when it started up again I was told it was still in recovery. I went through this loop a few times, and then I got it to work again, and synched successfully.
Since then, I have been unable to sync my iPod nano, although both iPod Classic and iPad work fine.
I have successfully synched the iPod on a laptop with Windows XP since then, but each time I connect it through VirtualBox I get the same error message.
I have tried disabling the iPod service in (the VirtualBox version of) Windows, and find that the iPod isn't being mounted as a disc drive, which is what happens in Ubuntu, and on my Windows XP laptop.
I've tried changing USB leads, and I've also booted Windows XP on my Ubuntu machine, and here iTunes recognises the iPod nano.
As far as I know, I made no changes to the configuration of VirtualBox between the time it was synching satisfactorily and the time it failed.
I don't think iTunes is at fault here, as the same version of iTunes syncs with the iPod nano on two different computers running Windows XP - I think it may be the way XP running in VirtualBox handles the mounting of the iPod.