I am not trying to insult anyone's intelligence with this, but let's see if everyone is on the same page with this.
When I go to Carnival.com it has the following at the top:
"Hey there, David / Guest #:xxxxxxxx / Login / Not David / My Profile / 1.888.CARNIVAL"
Login, Not David, and My Profile are hot links.
When I select My Profile I get a screen with a large area to create a user account with a smaller login area on the right side for existing accounts. I log in and it brings up the previously described screen with the options on the left side, which include cruise history.
Using a Mac I just accessed the Carnival page using three browsers (Camino, Firefox, and Safari). All three worked fine and gave me the same screens.
Would it be possible to create new profiles using a different e-mail address and password? My thought being the existing profiles are somehow damaged in the Carnival servers.