Username Colored Problem

On my forum, I am logged in and viewing my home page. One of my users username is shown in black. Their username is froggyhiphops. They are not a member of any group, or have any special permissions. I am very confused, and I am not sure why their namr is being displayed.
cbfanfun.forumotion.net

It's regular color as all the other members for me.

Dark, that doesnt tell me much

If you do: Admin panel >> users & Groups (tab) >> groups administration > and in there, there may be a group called "froggyhiphops" and permission for colouring is enabled.
Remove the group for the username colouring to disappear

EDIT:

the group may be a 'hidden' group, you cannot see it out side of the groups administration section

I just visited the site any that username you mentioned above is the same as any other normal member.

Different themes have different colours for standard members so they can stand out from the background.

None this has helped me. Froggyhiphops' username when I view it it is black, and everyone elses is blue. He doesn't have a group changing his color either. I viewed him on both my computors, logged in on my forum adn logged out and it's still black. I cant come to see why it is doing this. I think it may have something to do with the theme, but im not sure.

EDIT: I realized it is the theme. After you have clicked on a user, their name tirns black.