What's wrong with my sub-theme? I wanted to make some customizations to the "Seven" administration theme, so I started by installing the "Blossom" sub theme of Seven found here: http://drupal.org/project/blossom-admin . 

This worked fine.  So then I copied /sites/all/themes/blossom-admin and named it /sites/all/themes/myadmin

In the .info file for myamin, I changed

name = Blossom
description = Drupal Gardens administration theme.


to 

name = myadmin
destription = my description of this theme


And just to be safe, I also renamed any files that had the "blossom" name to "myadmin" in both the .info file and to the actual files themselves.  (Like renamed blossom.css to myadmin.css)

Now when I go to the Drupal admin and select myadmin as the administration theme, it works, but includes my main navigation and a footer region content at the top of the theme.  Does anyone know why this would happen to a straight copy of the blossom theme which worked fine?
Did you rename all the functions in the template.php file as well? These need to start with your theme name ;-)