Index: modules/forum/forum.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/forum/forum.install,v
retrieving revision 1.41
diff -u -p -r1.41 forum.install
--- modules/forum/forum.install	8 Jan 2010 15:58:43 -0000	1.41
+++ modules/forum/forum.install	25 Jan 2010 18:41:17 -0000
@@ -20,6 +20,9 @@ function forum_install() {
   variable_set('node_options_forum', array('status'));
 }
 
+/**
+ * Implements hook_enable().
+ */
 function forum_enable() {
   // Get info on the field "taxonomy_forums".
   $field_check = field_info_field("taxonomy_forums");
@@ -55,6 +58,16 @@ function forum_enable() {
     field_create_instance($instance);
 
     variable_set('forum_nav_vocabulary', $vocabulary->vid);
+
+    // Create a default forum so forum posts can be created.
+    $edit = array(
+      'name' => t('General discussion'),
+      'description' => '',
+      'parent' => array(0),
+      'vid' => $vocabulary->vid,
+    );
+    $term = (object) $edit;
+    taxonomy_term_save($term);
   }
 }
 
@@ -72,6 +85,7 @@ function forum_uninstall() {
   variable_del('forum_block_num_active');
   variable_del('forum_block_num_new');
   variable_del('node_options_forum');
+  variable_del('forum_nav_vocabulary');
 }
 
 /**
Index: modules/forum/forum.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/forum/forum.module,v
retrieving revision 1.553
diff -u -p -r1.553 forum.module
--- modules/forum/forum.module	14 Jan 2010 06:20:15 -0000	1.553
+++ modules/forum/forum.module	25 Jan 2010 18:41:18 -0000
@@ -281,6 +281,10 @@ function forum_node_validate($node, $for
       $containers = variable_get('forum_containers', array());
       foreach ($node->taxonomy_forums[$langcode] as $item) {
         $term = taxonomy_term_load($item['tid']);
+        if (!$term) {
+          form_set_error('taxonomy_forums', t('Select a forum.'));
+          continue;
+        }
         $used = db_query_range('SELECT 1 FROM {taxonomy_term_data} WHERE tid = :tid AND vid = :vid',0 , 1, array(
           ':tid' => $term->tid,
           ':vid' => $term->vid,