It worked about thirty minutes. I had opened new tabs in the window for comparisons and to select shelving options by their load capacity per shelf. No problems at that time.
Then it would sporadically show the error message for a couple of new tabs but when refreshed, it would go to the page. A couple minutes later, it stopped doing even that.
I had been sorting shelving according to load capacity per shelf in my "Lists". I'd created 4 or 5 lists maybe before it started acting up.
I've updated my browsers, Firefox and Chrome to make sure it wasn't an issue pertaining to that. I've rebooted my computer a couple times. The first time I had some Win7 updates being installed so I thought maybe it was that I may have needed an update. That didn't work the first time, so I rebooted again. Still coming up as the "HTTP Error 404. The requested resource is not found."