This particular error is crummy, sorry. What it really means is that the download timed out. This is usually caused by firewalls. Try disabling the firewall on your server and your client. Does it work then?
I'll try to reproduce this later tonight.
Edit: See, Solution: Get passive ftp working with filezilla server on windows server 2008
Also, make sure your routers allow incoming FTP connections to your server.
Tell me if that helps.