When I get a 404 page while logged into ShadowStalker it says that my name is Pk_JoA.
When this happened I was logged into ShadowStalker.
Pk_JoA is not a account of mine and I never heard of him before.
When I leave the 404 error page it says I am logged into ShadowStalker.
While I am on the 404 error page all links bring me back to being logged back into ShadowStalker.

Example:
Link to 404 error.
http://www.nonoba.com/chris​rac​ingvince10293s-game
Picture of what I see:
http://img443.imageshack.us/my.php?image=picture1yr4.png

More info.
It says that I have one message in my inbox when I am on the 404 error page.
When on any other page I don't have that message, so I think that it is Pk_JoA
(I can't read this message because clicking the inbox takes me back to my mail as ShadowStalker)