I was searching the forum to find a solution as to why Firefox repeatedly kept resetting (reverting) the proxy setting to "use system proxy setting" after I made a change to it. The answers that I came across did not help at all but through process of elimination - which included (refreshing Firefox, viewing and then deleting folders from my user profile , changing my start up items, enabling and disabling my firewall, enabling and disabling extensions and add ons, adding exceptions to various black list programs and firewall) - and ALL with no success - it finally dawned on me to check the proxy settings in my Google chrome and voila - a spam-ware program that I had quarantined and eliminated using Malware-bites had altered the Google setting to "use manual proxy" - which is shared across the computer. Once I set the Google to "use automatic detection" , Mozilla Firefox followed suit and the inability to connect was resolved. I wanted to add my discovery to one of the strings that didn't have a clear solution but I found it odd that I had to "FIGURE" out a way to post (instead of simply allowing me to register and add my discovery (solution) to the original string. Here is the string that I wanted to add to https://support.mozilla.org/en-US/questions/848905