By default all operating systems use port 21 for FTP transfers. If you run an FTP server, this could cause problems from conflicts. To resolve these conflicts, you should enable 'Web-Based FTP'. To do this go to the Registry and look for this string:
HKEY_CURRENT_USER\Software\Microsoft\FTP
Right-click on the 'Use Web Based FTP' value in the right pane and select 'Modify'. Change its value to 'Yes' then close the Registry and reboot your system for the changes to take effect.
