Do you mean you don't want people using Firefox on your computer to be able to switch into Private browsing? If so, see: https://support.mozilla.com/en-US/forum/1/493576?s=disable%20private%20browsing&as=q

You have or had an extension installed (NET_mmhpset) that has changed the user agent from Firefox/3.6 to Firefox/3.0.x. You can check the '''general.useragent''' prefs on the '''about:config''' page.<br /> You can open the ''about:config'' page via the location bar, just like you open a website.<br /> Filter: '''general.useragent'''<br /> If ''general.useragent'' prefs are bold (user set) then you can right-click that pref and choose ''Reset''. See : * [[Websites or add-ons incorrectly report incompatible browser]] * [[Finding your Firefox version]] See also: * http://kb.mozillazine.org/Resetting_your_useragent_string_to_its_compiled-in_default

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