Hello, yes that preference not exist anymore :(, but you can do that again if you install the next add-on : https://addons.mozilla.org/en-US/firefox/addon/new-tab-override/

after you install the add-on, open add-ons find that specific add-on and in URL type about:blank

Now when you click the + a new blank tab open.

thank you

Doesn't that button work at all or do you get the wrong page (about:newtab)?

Note that your System Details List shows multiple Flash plugins.

1. Shockwave Flash 17.0 r0
2. Shockwave Flash 19.0 r0

You can find the installation path of all plugins on the about:plugins page.

• http://kb.mozillazine.org/Issues_related_to_plugins#Identifying_installed_plugins

You can check the Flash player installation folder for multiple Flash player plugins and remove older version(s) of the plugin (NPSWF32) and possibly (re)install the latest Flash player.

• (32 bit Windows) C:\Windows\System32\Macromed\Flash\
• (64 bit Windows) C:\Windows\SysWOW64\Macromed\Flash\