I just thought of something...
This is a long shot, but I wonder if there's a "piece" of code left over on your account from when you were the administrator for the Sales Zone? The reason I say this is because, on my screen there is an extra column for me to use to manage posts. The difference is, on my administrative screen, that extra column has a check box, as shown here:
As I said, that's only when I sign in as an administrator. When I sign in as a non-administrative member, there is no extra column:
Has this extra column always been there, or did it recently appear? If it is recent, my theory is out the window.
Still, I'd like to know if anyone else is experiencing this so I can track it down.