Index: role_theme_switcher.module
===================================================================
--- role_theme_switcher.module	(revision 2608)
+++ role_theme_switcher.module	(working copy)
@@ -6,6 +6,9 @@
  */
 function role_theme_switcher_init() {
   global $user, $custom_theme, $theme;
+  
+  if( arg(0) == 'admin' && arg(2) == 'block') return;
+  
   foreach ($user->roles as $key => $value) {
     $role_name = str_replace(' ', '_', $value);
     $role_theme = variable_get(strtolower($role_name) .'_theme', '');