diff --git a/caps/src/nsScriptSecurityManager.cpp b/caps/src/nsScriptSecurityManager.cpp
index 6ecf30ca5bfb..b728ec012595 100644
--- a/caps/src/nsScriptSecurityManager.cpp
+++ b/caps/src/nsScriptSecurityManager.cpp
@@ -446,6 +446,14 @@ NS_IMETHODIMP
 nsScriptSecurityManager::CheckLoadURIFromScript(JSContext *cx, 
                                                 nsIURI *aURI)
 {
+    // Get a context if necessary
+    if (!cx)
+    {
+        cx = GetCurrentContextQuick();
+        if (!cx)
+            return NS_OK; // No JS context, so allow the load
+    }
+
     // Get principal of currently executing script.
     nsCOMPtr<nsIPrincipal> principal;
     if (NS_FAILED(GetSubjectPrincipal(cx, getter_AddRefs(principal)))) {
diff --git a/content/xml/document/src/nsXMLDocument.cpp b/content/xml/document/src/nsXMLDocument.cpp
index 95942f6e15e4..9237a2d564fe 100644
--- a/content/xml/document/src/nsXMLDocument.cpp
+++ b/content/xml/document/src/nsXMLDocument.cpp
@@ -46,6 +46,7 @@
 #include "nsIDOMComment.h"
 #include "nsIDOMElement.h"
 #include "nsIDOMText.h"
+
 #include "nsIDOMCDATASection.h"
 #include "nsIDOMProcessingInstruction.h"
 #include "nsIDOMDocumentType.h"
@@ -69,6 +70,8 @@
 #include "nsIParserFilter.h"
 #include "nsNetUtil.h"
 #include "nsDOMError.h"
+#include "nsScriptSecurityManager.h"
+#include "nsIPrincipal.h"
 
 
 // XXX The XML world depends on the html atoms
@@ -255,11 +258,24 @@ nsXMLDocument::Load(const nsAReadableString& aUrl)
 {
   nsCOMPtr<nsIChannel> channel;
   nsCOMPtr<nsIURI> uri;
-  nsresult rv = NS_OK;
+  nsresult rv;
   
-  // Create a new URI and channel
+  // Create a new URI
   rv = NS_NewURI(getter_AddRefs(uri), aUrl, mDocumentURL);
   if (NS_FAILED(rv)) return rv;
+
+  // Get security manager, check to see if we're allowed to load this URI
+  NS_WITH_SERVICE(nsIScriptSecurityManager, secMan, NS_SCRIPTSECURITYMANAGER_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) return rv;
+  if (NS_FAILED(secMan->CheckLoadURIFromScript(nsnull, uri)))
+    return NS_ERROR_FAILURE;
+
+  // Set a principal for this document
+  rv = secMan->GetCodebasePrincipal(uri, &mPrincipal);
+  if (!mPrincipal) return rv;
+  NS_ADDREF(mPrincipal);
+
+  // Create a channel
   rv = NS_OpenURI(getter_AddRefs(channel), uri, nsnull);
   if (NS_FAILED(rv)) return rv;
 
diff --git a/dom/src/base/nsGlobalWindow.cpp b/dom/src/base/nsGlobalWindow.cpp
index 50dd6bbbb206..29ab2aafc155 100644
--- a/dom/src/base/nsGlobalWindow.cpp
+++ b/dom/src/base/nsGlobalWindow.cpp
@@ -247,10 +247,17 @@ NS_IMETHODIMP GlobalWindowImpl::GetContext(nsIScriptContext ** aContext)
 
 NS_IMETHODIMP GlobalWindowImpl::SetNewDocument(nsIDOMDocument* aDocument)
 {
-  if (aDocument) {
-    nsCOMPtr<nsIDocument> doc(do_QueryInterface(aDocument));
-    if (doc)
+  if (!aDocument) {
+    if (mDocument) {
+      // Cache the old principal now that the document is being removed.
+      nsCOMPtr<nsIDocument> doc(do_QueryInterface(mDocument));
+      NS_ENSURE_TRUE(doc, NS_ERROR_FAILURE);
+
       doc->GetPrincipal(getter_AddRefs(mDocumentPrincipal));
+    }
+  } else {
+    // let go of the old cached principal
+    mDocumentPrincipal = nsnull;
   }
 
   // Always clear watchpoints, to deal with two cases:
@@ -512,33 +519,41 @@ NS_IMETHODIMP GlobalWindowImpl::HandleDOMEvent(nsIPresContext* aPresContext,
 
 NS_IMETHODIMP GlobalWindowImpl::GetPrincipal(nsIPrincipal** result)
 {
-  if (!mDocumentPrincipal && !mDocument) {
-    // If we don't have a principal and we don't have a document we
-    // ask the parent window for the principal. This can happen when
-    // loading a frameset that has a <frame src="javascript:xxx">, in
-    // that case we use the global window is used in JS before we've
-    // loaded a document into the window.
-    nsCOMPtr<nsIDOMWindow> parent;
-
-    GetParent(getter_AddRefs(parent));
-
-    if (parent && (parent.get() != NS_STATIC_CAST(nsIDOMWindow *, this))) {
-      nsCOMPtr<nsIScriptObjectPrincipal> objPrincipal(do_QueryInterface(parent));
-
-      if (objPrincipal) {
-        return objPrincipal->GetPrincipal(result);
-      }
-    }
-
-    return NS_ERROR_FAILURE;
-  }
-
   NS_ENSURE_ARG_POINTER(result);
 
-  *result = mDocumentPrincipal;
-  NS_ADDREF(*result);
+  if (mDocument) {
+    // If we have a document, get the principal from the document
+    nsCOMPtr<nsIDocument> doc(do_QueryInterface(mDocument));
+    NS_ENSURE_TRUE(doc, NS_ERROR_FAILURE);
 
-  return NS_OK;
+    return doc->GetPrincipal(result);
+  }
+
+  if (mDocumentPrincipal) {
+    *result = mDocumentPrincipal;
+    NS_ADDREF(*result);
+
+    return NS_OK;
+  }
+
+  // If we don't have a principal and we don't have a document we
+  // ask the parent window for the principal. This can happen when
+  // loading a frameset that has a <frame src="javascript:xxx">, in
+  // that case the global window is used in JS before we've loaded
+  // a document into the window.
+  nsCOMPtr<nsIDOMWindow> parent;
+
+  GetParent(getter_AddRefs(parent));
+
+  if (parent && (parent.get() != NS_STATIC_CAST(nsIDOMWindow *, this))) {
+    nsCOMPtr<nsIScriptObjectPrincipal> objPrincipal(do_QueryInterface(parent));
+
+    if (objPrincipal) {
+      return objPrincipal->GetPrincipal(result);
+    }
+  }
+
+  return NS_ERROR_FAILURE;
 }
 
 //*****************************************************************************
diff --git a/layout/xml/document/src/nsXMLDocument.cpp b/layout/xml/document/src/nsXMLDocument.cpp
index 95942f6e15e4..9237a2d564fe 100644
--- a/layout/xml/document/src/nsXMLDocument.cpp
+++ b/layout/xml/document/src/nsXMLDocument.cpp
@@ -46,6 +46,7 @@
 #include "nsIDOMComment.h"
 #include "nsIDOMElement.h"
 #include "nsIDOMText.h"
+
 #include "nsIDOMCDATASection.h"
 #include "nsIDOMProcessingInstruction.h"
 #include "nsIDOMDocumentType.h"
@@ -69,6 +70,8 @@
 #include "nsIParserFilter.h"
 #include "nsNetUtil.h"
 #include "nsDOMError.h"
+#include "nsScriptSecurityManager.h"
+#include "nsIPrincipal.h"
 
 
 // XXX The XML world depends on the html atoms
@@ -255,11 +258,24 @@ nsXMLDocument::Load(const nsAReadableString& aUrl)
 {
   nsCOMPtr<nsIChannel> channel;
   nsCOMPtr<nsIURI> uri;
-  nsresult rv = NS_OK;
+  nsresult rv;
   
-  // Create a new URI and channel
+  // Create a new URI
   rv = NS_NewURI(getter_AddRefs(uri), aUrl, mDocumentURL);
   if (NS_FAILED(rv)) return rv;
+
+  // Get security manager, check to see if we're allowed to load this URI
+  NS_WITH_SERVICE(nsIScriptSecurityManager, secMan, NS_SCRIPTSECURITYMANAGER_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) return rv;
+  if (NS_FAILED(secMan->CheckLoadURIFromScript(nsnull, uri)))
+    return NS_ERROR_FAILURE;
+
+  // Set a principal for this document
+  rv = secMan->GetCodebasePrincipal(uri, &mPrincipal);
+  if (!mPrincipal) return rv;
+  NS_ADDREF(mPrincipal);
+
+  // Create a channel
   rv = NS_OpenURI(getter_AddRefs(channel), uri, nsnull);
   if (NS_FAILED(rv)) return rv;