You should just be able to click and drag from your ipod in iTunes to your Library's Music folder - I know you can click and drag from Library -> Ipod, but not 100% sure if it will work backwards
Ill try some things and get back to you
Edit: That is weird that you can't copy from iPod to iTunes
I did some research on the internet and came across these following links :-
Ehow guide :-
http://www.ehow.com/how_2187421_transfer-music-ipod-itunes.html
Apple Support document :-
http://support.apple.com/kb/ht1329
Another way of doing it:-
http://www.mp3buzz.net/index.php/2006/06/27/how-to-get-songs-off-your-ipod-w-itunes/
I can't fully say which out of three will work best, but looks like all 3 will mean that you won't have to use software apart from iTunes
**Hopefully** you can have all your songs back on your computer in no time
