WPF Presentation Foundation designer Missing for the visual Studio

I could notice that the Intellisense for my xaml files are lost when i  opened a Silverlight UserControl in the default editor immediately after installing the Visual studio 2008,its SP1 and the Silverlight SDK 2.0. In fact, i was missing the  WPF Presentation Foundation designer in the “Open with” dialog Box.The default editor in place now then was the xml editor.

Thanks to visual studio command line help. I could made it working with the following command

Devenv /resetSkipPkgs

This command clears all options to skip loading added to VSPackages by users wishing to avoid loading problem VSPackages, then starts Visual Studio.