I assume that you already tried Safe Mode? *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes Check the connection settings. *Firefox > Preferences > Advanced > Network : Connection > Settings *https://support.mozilla.org/kb/Options+window+-+Advanced+panel If you do not need to use a proxy to connect to internet then try to select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly. See "Firefox connection settings": *https://support.mozilla.org/kb/Firefox+cannot+load+websites+but+other+programs+can You can check for problems with preferences and possibly reset all prefs. *http://kb.mozillazine.org/Preferences_not_saved *http://kb.mozillazine.org/Resetting_preferences ---- You may have an ISP that automatically redirects you to a search page if a DNS look up fails.<br /> That takes the control from Firefox to do the normal keyword search like a Google I'm Lucky search.<br /> In such cases you need to contact your ISP and ask for a DNS server to opt-out of that feature.<br /> You can also check if there is a link on the search results page to go to your ISP and opt-out. *http://en.wikipedia.org/wiki/DNS_hijacking

I tried resetting my preferences and clearing the history (I'm not sure if the latter had anything to do with this, but I'm mentioning it just in case), and now it seems to have been solved! Thank you!