Index: form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.190
diff -u -p -r1.190 form.inc
--- form.inc	24 Apr 2007 13:53:10 -0000	1.190
+++ form.inc	27 Apr 2007 02:24:25 -0000
@@ -686,7 +686,7 @@ function form_builder($form_id, $form) {
         if (!$form['#programmed'] || isset($edit)) {
           switch ($form['#type']) {
             case 'checkbox':
-              $form['#value'] = !empty($edit) ? $form['#return_value'] : 0;
+              $form['#value'] = !empty($edit) ? $form['#return_value'] : NULL;
               break;
 
             case 'select':
@@ -733,7 +733,7 @@ function form_builder($form_id, $form) {
           $function($form);
         }
         else {
-          $form['#value'] = isset($form['#default_value']) ? $form['#default_value'] : '';
+          $form['#value'] = isset($form['#default_value']) ? $form['#default_value'] : NULL;
         }
       }
     }
@@ -1308,7 +1308,7 @@ function theme_checkbox($element) {
   $checkbox .= 'name="'. $element['#name'] .'" ';
   $checkbox .= 'id="'. $element['#id'] .'" ' ;
   $checkbox .= 'value="'. $element['#return_value'] .'" ';
-  $checkbox .= $element['#value'] ? ' checked="checked" ' : ' ';
+  $checkbox .= isset($element['#value']) ? ' checked="checked" ' : ' ';
   $checkbox .= drupal_attributes($element['#attributes']) .' />';
 
   if (!is_null($element['#title'])) {
@@ -1351,7 +1351,7 @@ function expand_checkboxes($element) {
     }
     foreach ($element['#options'] as $key => $choice) {
       if (!isset($element[$key])) {
-        $element[$key] = array('#type' => 'checkbox', '#processed' => TRUE, '#title' => $choice, '#return_value' => $key, '#default_value' => isset($value[$key]), '#attributes' => $element['#attributes']);
+        $element[$key] = array('#type' => 'checkbox', '#processed' => TRUE, '#title' => $choice, '#return_value' => $key, '#default_value' => isset($value[$key]) ? $value[$key] : NULL, '#attributes' => $element['#attributes']);
       }
     }
   }