see if any of these can help. http://kb.mozillazine.org/Unable_to_save_or_download_files http://www.ehow.com/how_11385212_troubleshoot-reset-connection-firefox.html https://support.mozilla.org/en-US/kb/server-not-found-connection-problem https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can 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.

No dice. This is an issue specifically with my Mac connecting to our SharePoint server. I'm hoping to fix it with a change in Firefox's about:config settings. An earlier issue I had with my Mac connecting to our SharePoint system overall was corrected by altering the network.negotiate-auth.allow-insecure-ntlm-v1 line, but this problem seems to be something new!