No idea about the main problem but the FireFox tab issue is probably to do with the recent version update where new tabs do not open with your homepage any more (that option has been removed 
) or blank unless you change the settings.
New tabs now open with unwanted by many users ‘suggestion’ pane links based on your web site visiting habits. My guess is that one or more of those panes, even the same one, is being similarly blocked and that’s why you get that message.
If you want a new tab to load your homepage then a simple way I was made aware of only a few weeks ago is to move the cursor to the tab bar and use middle mouse click (click down on the mouse wheel).
But to stop the annoying ‘suggestion’ panes in new tabs opened in the normal way unfortunately there’s no FireFox about:config fix you have to install a third party add-on now. I use:-
https://addons.mozilla.org/en-US/firefox/addon/new-tab-homepage/
Works perfectly.
