Index: adaptivetheme/adaptivetheme/inc/template.theme-overrides.inc
===================================================================
--- adaptivetheme/adaptivetheme/inc/template.theme-overrides.inc	(revision 961)
+++ adaptivetheme/adaptivetheme/inc/template.theme-overrides.inc	(working copy)
@@ -98,7 +98,7 @@ function adaptivetheme_button($element) 
   }
 
   // Wrap visible inputs with span tags for button graphics
-  if (stristr($element['#attributes']['style'], 'display: none;') || stristr($element['#attributes']['class'], 'fivestar-submit')) {
+  if ((isset($element['#attributes']['style']) && stristr($element['#attributes']['style'], 'display: none;')) || stristr($element['#attributes']['class'], 'fivestar-submit')) {
     return '<input type="submit" '. (empty($element['#name']) ? '' : 'name="'. $element['#name'] .'" ')  .'id="'. $element['#id'] .'" value="'. check_plain($element['#value']) .'" '. drupal_attributes($element['#attributes']) ." />\n";
   }
   else {