cannot access internet after update

         Firefox can't establish a connection to the server at www.facebook.com.
       

 The site could be temporarily unavailable or too busy. Try again in a few
   moments.
 If you are unable to load any pages, check your computer's network
   connection.
 If your computer or network is protected by a firewall or proxy, make sure
   that Firefox is permitted to access the Web.

I received an update to Firefox last week. Ever since, when I try to use Firefox to access the internet, I receive the following message: Unable to connect Firefox can't establish a connection to the server at www.facebook.com. The site could be temporarily unavailable or too busy. Try again in a few moments. If you are unable to load any pages, check your computer's network connection. If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.