The required disk cannot be found - I can't sync my iPod

Follow these steps exactly and you should have an iPod free from the dreaded "Disk not available" error! Please note that I've only encountered this problem on my iPod Shuffle (2nd Gen), so have only been able to confirm this working on that, YMMV.

To begin with, ensure iTunes is not running, and your iPod is not connected. Make sure you read through the following steps before your begin.

1. Run "c:\WINDOWS\system32\devmgmt.msc" (this is the Device Manager), this will need to be used later, but you'll need it quickly when you do.
2. Start iTunes
3. Connect iPod
4. Go to your iPod Settings and select "Enable disk use"
5. A dialog box will pop up reminding you that you'll need to manually eject. Hit OK
6. Hit Apply to save changes to the iPod
7. Quickly switch to Device Manager window and right-click on any item there and select "Scan for hardware changes"
8. Switch back to iTunes, where you should have a nice, working iPod!

Hope this helps everyone, please post you results

Sources: http://discussions.apple.com/thread.jspa?messageID=6381890