Notification events are getting deleted while the message is still within drupal queue.

+++ b/notifications.cron.incundefined
@@ -79,20 +79,56 @@ function notifications_process_prepare() {
+    // Get all the existing items within the queue.
+    $result = db_query("SELECT data FROM {queue} WHERE name='notifications_event'");
+    $queues = array();
+    while ($queue = db_fetch_object($result)) {
+      $queue->data = unserialize($queue->data);
+      if (isset($queue->data->node)) {
+        $nid = intval($queue->data->node->nid);
+        $queues[$nid] = $nid;
+      }
+    }
+
+    // Get all of the event items.
+    $result = db_query("SELECT * FROM {notifications_event}");
+    $events = array();
+    while ($event = db_fetch_object($result)) {
+      $event->params = unserialize($event->params);
+      $nid = intval($event->params['nid']);
+      $events[$event->eid] = $nid;

It may be worth considering wrapping this in a if module_exists('drupal_queue') or some other way to tell that notifications is using drupal_queue rather than it's defaults...