The Conduit Plugin and the associated preference changes don't become installed all by themselves. You need to be more careful when deciding what add-ons or programs you install. To fix Firefox the first thing to do is to remove that Entrusted Toolbar extension through the Extensions tab of the Add-on manager. https://support.mozilla.org/en-US/kb/remove-toolbar-has-taken-over-your-firefox-search Then install the Search Reset extension - https://addons.mozilla.org/en-US/firefox/addon/searchreset/ Then fix the about:newtab preference - https://support.mozilla.org/en-US/kb/new-tab-page-show-hide-and-customize-top-sites#w_how-do-i-turn-the-new-tab-page-off - and instead of double-clicking that preference, right-click that pref and select Reset.

You can check in "Windows Control Panel > Programs" for recently installed programs (sort by "Installed on") to see if anything from Conduit or any other suspicious software shows up.