If you use IE in 10.1, you may find that on some FTP links that IE will hang with a message stating "Set passive mode" at the bottom of the window. If this happens to you, you should be able to fix the problem through your System Preferences.
Load the Network preference panel, click on the Proxies tab, and make sure the checkbox that reads "Use Passive FTP Mode (PASV)" is checked.
This should allow passive FTP downloads within Explorer on 10.1.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011015224222165