Run Firefox …
At the top of the Firefox window, click the “Firefox” button,
go over to the “Help” sub-menu
(on Windows XP, click the Help menu at the top of the Firefox window) and select “Troubleshooting Information”.
Click the “Reset Firefox” button in the upper-right corner of the Troubleshooting Information page.
click “Reset Firefox” in the confirmation window that opens.
Firefox will close and be reset. When it’s done. Click “Finish” and Firefox will open.
When I come to this website the gigantic Xfinity box is back, so the problem persists.
I don’t understand this.
Can you please clarifying a bit better?