With FF3, new about: handlers need to implement getURIFlags. Also typo in XUL file

extensions/cck/browser/resources/content/cckwizard/cckwizard.xul

@@ -76,7 +76,7 @@
      </hbox>
      <hbox>
        <button label="&newConfig.label;" id="newconfig" oncommand="CreateConfig();"/>
-       <button label="&copyConfig.label;" id="copyconfig" oncommand="CopyConfig();"/>/>
+       <button label="&copyConfig.label;" id="copyconfig" oncommand="CopyConfig();"/>
        <button label="&deleteConfig.label;" id="deleteconfig" oncommand="DeleteConfig();"/>
      </hbox>
      <checkbox id="saveOnExit" label="&saveOnExit.label;" oncommand="SetSaveOnExitPref();"/>

extensions/cck/browser/resources/content/cckwizard/srcfiles/disableAboutConfig.js.in

@@ -60,6 +60,9 @@ AboutHandler.prototype =
     var ext_uri = ioService.newURI(uri_str, null, null);
     var ext_channel = ioService.newChannelFromURI(ext_uri);
     return ext_channel;
+  },
+  getURIFlags : function getURIFlags(aURI) {
+    return Components.interfaces.nsIAboutModule.URI_SAFE_FOR_UNTRUSTED_CONTENT;
   }
 };