by SirArchmage Tue Jul 30, 2013 8:35 pm
It randomly happens at times, and it most likely is random. Glitch that happens, and is much more likely to happen if doing anything else online related, like summoning a phantom.
It is also much easier and reliable to check to see if you can quit the game to know if someone is in your world. Because your soap stones and homeword bone will be blacked out to show you cannot use them, yes, but that can also mean that you are in "Dark Souls Limbo", basically on the waiting list queue to get invaded. While you are in Limbo, you cannot use bonfires, use homeward bones, summon signs, or eye orbs, and no one is currently in your world. You can, however, quit the game. You cannot quit the game though if someone is actively roaming in your world.