The location/address bar shows the onlinezakladki.ru site. I assume that this is currently your new tab page, either set by you or by an extension (malware). You can check the browser.newtab.url preference on the <b>about:config</b> page. You can reset user set (bold) prefs via the right-click context menu to the default value or set another page as the new tab page. See this article about the New Tab page (about:newtab): *https://support.mozilla.org/kb/new-tab-page-show-hide-and-customize-top-sites You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I'll be careful" to continue. *http://kb.mozillazine.org/about:config You can check for recently installed suspicious or unknown extensions. *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes If you do not keep changes after a restart or otherwise have problems with preferences, see: *http://kb.mozillazine.org/Preferences_not_saved