Index: sites/all/modules/comment_display/comment_display.module
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- sites/all/modules/comment_display/comment_display.module	(revision 1274)
+++ sites/all/modules/comment_display/comment_display.module	(revision )
@@ -14,9 +14,12 @@
 function comment_display_menu_alter(&$callbacks) {
   // Skip this if Page Manager exists; comment_display_preprocess_page() will
   // still work.
-  if (!module_exists('page_manager') && $callbacks['node/%node']['page callback'] == 'node_page_view') {
+  if ($callbacks['node/%node']['page callback'] == 'node_page_view') {
     $callbacks['node/%node']['page callback'] = 'comment_display_node_page_view';
     $callbacks['node/%node/revisions/%/view']['page callback'] = 'comment_display_node_show';
+  }
+  else {
+    watchdog('comment_display', 'Cannot disable core display of comments as another module has already overridden the default node view callback.');
   }
 }