Skuzzy, I think you answered another question than the one ozrocker was asking.
I noticed it too, but it was too fast for my aging eyes to see what it was. Now that ozzie gave a clue, I finally could get a glimpse: Right after clicking "Online arenas" a window pops up, giving advice to re-enable AH in ZoneAlarm or other firewall program. The problem is, this splash screen now only shows for a fragment of a second, not giving the slightest opportunity to click any of the buttons within.
Good thing is, it doesn't affect gameplay unless such a firewall is used and the user is unaware of this firewall feature.