The following errors are returned when using Internet Explorer (IE) as an explicit FTP proxy:
Error: Internet Explorer was not able to open this internet site...
Error: Page cannot be displayed
Error: Windows cannot access this folder
Error: Page not found
These are known issues with Internet Explorer that occurs when using an explicit proxy and accessing FTP sites that require a login.
As a workaround you will need to specify the username and password in the address bar. See 000008756 for more information on this workaround.