FF Connection settings not remembered on new browser session

Every time I open up a FF browser, I have to go to Tools --> Advanced-->Settings and 开发者_开发问答change the proxy setting to No Proxy. Why FF does not remember the settings?

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Two possibilities come to mind:

1. You have a user.js override for network.proxy.type that resets it every time you restart.
2. Your Firefox is configured to use the system preference service.