Suppose I open tabs B and C from different links in tab A. Sometimes, when I switch to one of them, say tab B, I'll get a popup saying that something went wrong loading the tab, and I can have Firefox reload it. After I reload it, tab B loads and renders fine. Tab A as gone one step back in its history. The "forward" button is grayed out in that righthand panel. If I switch to tab C, I see a blank white page, with the URL of the page in the address bar (not the page title). The thumbnail shows the correct page. If I try to reload the page, it does not reload the page (page stays blank, finishes immediately), and it clears the URL so that it then says "Enter Search or Address". Alternatively, if I do not try to refresh it and instead tap the address bar, the awesome screen shows up, but the address bar is blank.