Unable to connect
Firefox can't establish a connection to the server at ad.doubleclick.net.
* The site could be temporarily unavailable or too busy. Try again in a few
* If you are unable to load any pages, check your computer's network
* If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web
"Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"
"Remove the Cookies" from sites that cause problems: Tools > Options > Privacy > Cookies: "Show Cookies"
Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).
See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems
Clearing the Cache and removing Cookies is only a temporary solution. Restart the computer and the problem persists.
Incidentally this is not a problem for Internet Explorer - just Firefox.