--- mozilla-central/browser/base/content/utilityOverlay.js.checkupdates	2010-11-04 21:05:17.000000000 +0100
+++ mozilla-central/browser/base/content/utilityOverlay.js	2010-11-06 10:49:40.172670752 +0100
@@ -525,7 +525,7 @@
 
   // Disable the UI if the update enabled pref has been locked by the 
   // administrator or if we cannot update for some other reason
-  var canCheckForUpdates = updates.canCheckForUpdates;
+  var canCheckForUpdates = updates.canCheckForUpdates && updates.canApplyUpdates;
   checkForUpdates.setAttribute("disabled", !canCheckForUpdates);
   if (!canCheckForUpdates)
     return;