*  If you don't connect to the Internet through a proxy (or don't know whether you connect through a proxy), select No Proxy.
      *  If you connect to the Internet through a proxy, compare Firefox's settings to another browser's (such as Safari — depending on your OS X version, see Mac OS X 10.6: Enter proxy server settings, OS X Lion: Enter proxy server settings, or OS X Mountain Lion: Enter proxy server settings). 

Hello... This article describes problems where Firefox cannot load websites but other Web browsers (such as Safari) can. When this happens, Firefox may show a Server not found or Unable to connect error message. * For other error messages that display when you try to view websites in Firefox, see Websites don't load - troubleshoot and fix error messages. * If none of the Web browsers on your computer can load websites, see Firefox and other browsers can't load websites. '''Internet Security software blocking Firefox''' If you were able to load websites until you updated Firefox or until your Internet security software was updated, reconfigured or a new one was added, your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is likely preventing Firefox from connecting to the Internet. '''Firefox connection settings''' If you connect to the Internet through a proxy server that is having connection problems, you will not be able to load websites. To check your connection settings in Firefox: # Click the menu button Fx57Menu and select Preferences. # In the General panel, go down to the Network Settings section. # In the Network Settings section, click Settings…. # Change your proxy settings: * If you don't connect to the Internet through a proxy (or don't know whether you connect through a proxy), select No Proxy. * If you connect to the Internet through a proxy, compare Firefox's settings to another browser's (such as Safari — depending on your OS X version, see Mac OS X 10.6: Enter proxy server settings, OS X Lion: Enter proxy server settings, or OS X Mountain Lion: Enter proxy server settings). 5. Close the Connection Settings dialog.<br> 6. Close the about:preferences page. Any changes you've made will automatically be saved. If you find that changes you make to your Firefox connection settings are not remembered when you restart Firefox, see How to fix preferences that won't save.