Over the last year there has been a substantial increase in the number of sites on the internet that have been hacked due to viruses that steal FTP credentials from user's home computers. The hackers then use these credentials to insert hidden code within your website. Please see http://en.wikipedia.org/wiki/Gumblar for more information on this type of attack. To reduce the significant threat from these viruses the solution is to sensibly lock FTP when it's not in use, making it extremely difficult for the hackers to infect your site via this route. To unlock FTP, customers will simply log into their control panel and click one button to unlock FTP for a period of time. FTP will then automatically lock again after the time period has expired.