See:

• http://kb.mozillazine.org/Error_loading_websites

You can try to reset (power off/on) the router.

Not a router issue. Seems to be an issue with google groups and/or firefox. Doesn't load on IE either. All browsers are up to date and addons were disabled, re-enable, etc.

Very frustrating

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

Which security software (firewall, anti-virus) do you have?

Tried the cache clear and still happening.

Using etrust through a network for antivirus

Try to remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.com/kb/Server+not+found
• https://support.mozilla.com/kb/Firewalls