The forums will be running fine and then suddenly everyone will get the "The requested page could not be found." error for anywhere from 30 seconds to 5 minutes. After that, everything will start working fine again. No error logs of any kind are made, at least none that I can find. No add-ons are installed, the ACP isn't opened, so I'm not sure what's causing it. The frequency seems to be random as well. The most frequent is two or three times in 10 minutes, though the average length of time between errors is a few hours. It even happened to me last night when I was the only one online. I was tabbed out for a few minutes, tabbed back in, hit refresh, then hit the error.