Do you get any kind of message?

There is security software like Avast and Kaspersky and 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/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.

Never get any message - nothing happens when you try to open some Web pages. Some Web pages work ok. I am using Avast Anti-Malware.

Try to disable the web shield in the Avast settings.

• http://www.ghacks.net/2014/10/31/avasts-https-scanning-interferes-with-firefox-and-other-programs/

Open the Avast dashboard on the affected system.
Select Settings from the left sidebar menu.
Switch to Active Protection.
Click on Customize next to Web Shield.
Uncheck the "Enable HTTPS Scanning" option and click OK.

Followed suggestion to disable HTTPS and still cannot open some sites. Strange thing with Fidelity site - I can go to search bar at top of page and search for Fidelity and then open the site from the link on the Yahoo search page. Most of the web sites still work OK with Firefox but several will not open.

Compare the two links. Post them if you want.

here is link when I do a search for Fidelity and results come up in Yahoo Search - this link works ok https://www.fidelity.com/mutual-funds/fidelity-funds/overview?imm_pid=700000001009647&immid=100144&imm_eid=e5737180620&gclid=CJPn3vqOqsoCFWYrMgod5q4JGw&gclsrc=ds

here is link when I try to go to Fidelity direct https://www.fidelity.com/ with this link, nothing happens and no messages

https://www.fidelity.com works fine for me. The search link opens; https://www.fidelity.com/mutual-funds/fidelity-funds/overview (Does this link work for you?)

Something is blocking you.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
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