I registered yesterday and received the "Action Required" email, so I clicked on the link to activate my account. This worked and I received the "Welcome" email telling me I had successfuly registered. I signed in today and was unable to do anything except read the posts. Everything I clicked on asked for my user name and password. They were accepted, but still nothing worked and the login boxes remained at the top of the screen.
Then I read a post from Jeff, I believe, and tried the link he suggested and suddenly everything worked! I am using Internet Explorer version 8, and I had been clicking on the "Message Board" link on the Couples home page. That links you you page http://www.couples.com/08messageF.htm, which seams to be the problem when using Internet Explorer.
If you use the following link from Jeff, everything should work fine.