When a user logs out of the board, would you know why it still shows the previous person in the upper left hand corner and a square for the non-existant avatar? It seems like something is holding the values even though it is asking for the person to log in to post.
This screen shot is with me logged out of the entire WP site and forum.
SITE: http://junks.tv
It knows who you are because of the cookie on your system.
In the forum admin > Options > Member Settings is an option to disallow members not logged in to post as guests. If you turn that off it should not demand you log in if that is the bit you do not like.
I am unsure about the missing avatar though. I assume when logged in you do have an avatar? and if so where does it come from?