Index: branches/5.1.x/core/admin_templates/js/forms.js
===================================================================
diff -u -N -r12127 -r12657
--- branches/5.1.x/core/admin_templates/js/forms.js	(.../forms.js)	(revision 12127)
+++ branches/5.1.x/core/admin_templates/js/forms.js	(.../forms.js)	(revision 12657)
@@ -62,8 +62,8 @@
 	// process all FCKEditor instances
 	var iframes = document.getElementsByTagName('IFRAME');
 
-	for (var i=0; i<iframes.length; i++) {
-		if (iframes[i].id.match(/___Frame$/)) {
+	for (var i = 0; i < iframes.length; i++) {
+		if (iframes[i].id.match(/___Frame$/) && iframes[i].getAttribute('latesrc')) {
 			iframes[i].contentWindow.location = iframes[i].getAttribute('latesrc');
 		}
 	}
@@ -90,6 +90,9 @@
 
 Form.Init = function(id) {
 	this.Div = document.getElementById(id);
+	if (!this.Div) {
+		return ;
+	}
 
 	for (var i = 0; i < this.Controls.length; i++) {
 		dim = getDimensions( document.getElementById(this.Controls[i]) );
@@ -200,8 +203,11 @@
 	return parseInt($size);
 }
 
-Form.Resize = function()
-{
+Form.Resize = function() {
+	if (!this.Div) {
+		return ;
+	}
+
 	var h = (document.all ? window.document.body.offsetHeight : window.innerHeight);
 
 	var $div = $(this.Div);