diff -r -u subscriptions-orig/subscriptions_content.module subscriptions/subscriptions_content.module
--- subscriptions-orig/subscriptions_content.module	2009-07-19 19:14:12.000000000 +0200
+++ subscriptions/subscriptions_content.module	2009-07-19 18:23:52.000000000 +0200
@@ -751,22 +751,24 @@
     $subscriptions[$s['nid']][$s['author_uid']] = $s;
   }
 
-  // check whether we've commented:
-  $nids = array_keys($subscriptions);
-  $placeholders = db_placeholders($nids);
-  $result = db_query("
-    SELECT nid FROM {comments}
-      WHERE
-        nid IN (
-          SELECT ". ($GLOBALS['db_type'] == 'pgsql' ? 'CAST(' : '')
-               ."value". ($GLOBALS['db_type'] == 'pgsql' ? ' AS INTEGER)' : '')
-                    ." FROM {subscriptions} WHERE module = 'node' AND field = 'nid' AND recipient_uid = %d
-        )
-        AND uid = %d GROUP BY nid", $uid, $uid);
-  while ($c = db_fetch_array($result)) {
-    if (isset($subscriptions[$c['nid']])) {
-      foreach ($subscriptions[$c['nid']] as $author_uid => $subscription) {
-        $subscriptions[$c['nid']][$author_uid]['commented'] = TRUE;
+  if (count($subscriptions)) {
+    // check whether we've commented:
+    $nids = array_keys($subscriptions);
+    $placeholders = db_placeholders($nids);
+    $result = db_query("
+      SELECT nid FROM {comments}
+        WHERE
+          nid IN (
+            SELECT ". ($GLOBALS['db_type'] == 'pgsql' ? 'CAST(' : '')
+                 ."value". ($GLOBALS['db_type'] == 'pgsql' ? ' AS INTEGER)' : '')
+                      ." FROM {subscriptions} WHERE module = 'node' AND field = 'nid' AND recipient_uid = %d
+          )
+          AND uid = %d GROUP BY nid", $uid, $uid);
+    while ($c = db_fetch_array($result)) {
+      if (isset($subscriptions[$c['nid']])) {
+        foreach ($subscriptions[$c['nid']] as $author_uid => $subscription) {
+          $subscriptions[$c['nid']][$author_uid]['commented'] = TRUE;
+        }
       }
     }
   }
@@ -801,10 +803,10 @@
       subscriptions_form_helper($form[0], $defaults, $author_uid, $subscription['nid'], $title, $subscription);
     }
   }
-  $form[0]['extra_info']['#title'] = t('Latest activity, authored, commented');
   unset($form[0]['author']);
 
   if (count(element_children($form[0]))) {
+    $form[0]['extra_info']['#title'] = t('Latest activity, authored, commented');
     $form[0]['defaults'] = array(
       '#type' => 'value',
       '#value' => $defaults,