--- advancedbookblocks.module
+++ advancedbookblocks.module
@@ -99,7 +99,7 @@
     $links[] = l(t('Configure'), 'admin/settings/advanced-book-blocks/configure/'. $book->delta);
     $links[] = l(t('Reset'), 'admin/settings/advanced-book-blocks/reset/'. $book->delta.'-'.$token);
     if ($book->delta != 0) {
-      $links[] = l(t(Delete), 'admin/settings/advanced-book-blocks/delete/'. $book->delta.'-'.$token);
+      $links[] = l(t('Delete'), 'admin/settings/advanced-book-blocks/delete/'. $book->delta.'-'.$token);
     }
     $row[]   = implode('    ', $links);
     $rows[]  = $row;
@@ -558,8 +558,11 @@
  * Implementation of hook_nodeapi().
  */
 function advancedbookblocks_nodeapi(&$node, $op) {
+    
+  //check to see if node is a book
+  if (!empty($node->book['bid'])) {
+    $bid = $node->book['bid']; 
   
-  $bid = $node->book['bid']; 
   if ($op == 'update' || $op == 'insert' ) {
    
     if (!empty($bid) && ($bid == $node->nid)) {
@@ -642,5 +645,5 @@
       }
     }
   
-  
+ } 
 }
\ No newline at end of file