What is your computer system and Firefox? There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate. http://www.ehow.com/how_11385212_troubleshoot-reset-connection-firefox.html https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message https://support.mozilla.org/en-US/kb/connection-untrusted-error-message '''http://kb.mozillazine.org/Error_loading_websites''' '''This Connection is Untrusted''' is sometimes caused because the computer system clock is wrong. Check the time / date / time zone settings.

hello, a solution depends on the individual circumstances: * what is the '''error code''' shown when you click on ''advanced'' on that error page? * like shown in the screenshot, please also give us more information about the error by clicking on the error code, copying the text to the clipboard and then pasting it here into a reply in the forum. thank you!