wow, GiaToria is faaast. Meanwhile, I clicked the Join button once, went to find the group, failed, came back, clicked the Join button again, and now I get "server_error"! :O
I am also getting server error when I try to join this group. If I go into Groups and then a particular group, I can see the avatars for members but not their names.
Submit a bug report with details on what you're seeing--they'll get to it when they have a chance. I already posted one about not being able to join the two groups.