that link worked for me. I only get that pop-up when I log off. I log back on, click the don't show this again deal, and it is gone until I log off again.
Ok, for the people saying the "Don't show this again" button doesn't work, that's a cookie issue on your browser's part. It's most probably that you have your browser set to clear cookies after every session (as I do - but I have it like that on purpose).
I use safari, and every time I visit the main page of this site it shows that message. Even if I click "do not show this again" it keeps coming back. By the way I am using pop-up blocker. This doesn't bother me at all anyways.