Well this is not a Critical bug, but is still a big problem with the forum.
Since a few months Happened to me that PBE Forum clash with Other regions LOL Forums.
I always could have both Forums, PBE one and Any other,NA/LAS/LAN/EUW/ETC open at the same time, But since a few Months one or the other tend to appear first, and If I log out from one, I the other activates itself until both are logged out.
A month ago this problem got fixed somehow, but this Week It came back.
So now, for posting here, I must log out from other LOL forums, and to use those I must Log out from PBE...
So maybe is the Site, or could be my Cookies?
EDIT: I Delete LOL Cookies, but the problem still Persist.
EDIT2: The user "pbeDrakari" post a way how to fix this, and it works: **log out on both Boards in separate tabs, then log into each Forums in separate tabs.