If firefox has "use system proxy setting' configured to access the internet, where does it get the info from(e.g.windows regitry?)?
Does firefox cache the pac file? If yes, where? What if the proxy server is not accessible?
Separate Issue; Update your Flash Player v126.96.36.1996
A proxy is for when the computer does not have direct access to the web. If one is not needed, then the setting would be No Proxy.
Your computer should have a Network Control window thru the Control Panel.
If you are having problems, just ask for help.