Just in case you have recently updated to FF16 you are advised to downgrade to FF15.1 due to a serious security flaw.
The latest version of Mozilla's Firefox browser has been taken offline after a security vulnerability was discovered.
Users who had upgraded to version 16 were advised to downgrade to the previous safe release until Firefox developers released a fix.
The vulnerability allowed "a malicious site to potentially determine which websites users have visited", Mozilla said.
The non-profit company said that only a "limited number of users are affected".
Full story here: http://www.bbc.co.uk/news/technology-19909106