Net weirdness I guess. Was time to reboot the PC anyways (do it every few days). Closed the browser, rebooted, reopened browser (SeaMonkey), but still saw the error screen. Just for giggles, I decided to try it in IE. That worked fine and got the normal screen, flipped back to the tab in SM and the normal screen was there. I had not changed anything in SM, not even refreshing/reloading the tab.
Oh well.