Index: accesschk.c
===================================================================
--- ntoskrnl/se/accesschk.c	(revision 70096)
+++ ntoskrnl/se/accesschk.c	(working copy)
@@ -425,8 +425,17 @@
     if (DesiredAccess == 0)
     {
         *GrantedAccess = PreviouslyGrantedAccess;
-        *AccessStatus = STATUS_SUCCESS;
-        ret = TRUE;
+        if (PreviouslyGrantedAccess == 0)
+        {
+            DPRINT1("XXX: Failing access check for DesiredAccess=0\n");
+            *AccessStatus = STATUS_ACCESS_DENIED;
+            ret = FALSE;
+        }
+        else
+        {
+            *AccessStatus = STATUS_SUCCESS;
+            ret = TRUE;
+        }
     }
     else
     {
Index: comcat.c
===================================================================
--- dll/win32/ole32/comcat.c	(revision 70096)
+++ dll/win32/ole32/comcat.c	(working copy)
@@ -229,7 +229,7 @@
 	if (res != ERROR_SUCCESS) return S_FALSE;
 	for (string = impl_strings; *string; string += CHARS_IN_GUID) {
 	    HKEY catkey;
-	    res = open_classes_key(subkey, string, 0, &catkey);
+	    res = open_classes_key(subkey, string, READ_CONTROL, &catkey);
 	    if (res != ERROR_SUCCESS) {
 		RegCloseKey(subkey);
 		return S_FALSE;