Check the address for typing errors such as ww.example.com instead of www.example.com
   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.

Just update to 43.0.2 lastnight and this am firefox cant connect to any web pages(IE connects fine still)Running Vista Still but didnt have a issue until I updated to 43.0.2, Have no proxy and no firewalls no secuity at all on this pc and tried all the sugested solutions in support still will not connect to any web page! Does firefox not support vista now with this update and if now then atleast allow someone to roll back to prior update(atleast then can use firefox, .useless program if it wont connect to web pages once update) says Server not found Firefox can't find the server at www.yahoo.com. Check the address for typing errors such as ww.example.com instead of www.example.com 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.