The article [Q328785] explains that when you use IE to connect to a File Transfer Protocol (FTP) site that requires authentication, you may not be able to connect to the site because:
a. When you connect to an FTP site, IE first sends anonymous credentials to see if a connection can be established. In most cases, IE can connect using anonymous credentials. However, if the FTP site requires credentials, IE prompts you for credentials again because the anonymous credentials that are sent are not successful.
b. However, if the Show friendly HTTP error messages option on the Advanced tab of Internet Options is turned on, IE does not generate an Authentication dialog box for you to enter the correct user name and password. Because you are not prompted to reauthenticate to the FTP site, you cannot connect to the site and you receive the error message:
The page cannot be displayed