One of our users mistakenly installed Google Chrome when installing an Adobe update and then uninstalled it. However the uninstall did not restore all of the Internet Explorer setting causing multiple problems. One issue was that the user could not use Windows Explorer to view an ftp site.
When the user logged into an ftp site and went to "View" and then "Open ftp site in Windows Explorer" nothing would happen. After searching for this issue we found others had a similar problem and were able to export the registry key [HKEY_CLASSES_ROOT\ftp] and then import it into the computer that was having issues. In our case the [HKEY_CLASSES_ROOT\ftp] registry key was missing entirely from the user's computer and needed to be recreated.