Index: /FCKeditor/trunk/editor/_source/internals/fckdomtools.js
===================================================================
--- /FCKeditor/trunk/editor/_source/internals/fckdomtools.js	(revision 525)
+++ /FCKeditor/trunk/editor/_source/internals/fckdomtools.js	(revision 526)
@@ -39,5 +39,5 @@
 		// If the node is a <pre>, ignore. Whitespaces in the beginning or tail of a <pre> tag
 		// shows up as in HTML code so we shouldn't delete them.
-		if ( node.tagName.toLowerCase() == 'pre' )
+		if ( node.nodeType == 1 && node.tagName.toLowerCase() == 'pre' )
 			return ;
 		this.LTrimNode( node ) ;