Howto: “Object not set to an instance of an object” in Visual Studio 2008 when trying to add a Silverlight project to a solution

I installed Visual Studio 2008 SP1 Beta, .Net 3.5 SP1 Beta and the new Silverlight Tools Beta 2, and when I tried to add a new Silverlight project to my solution I got a dialog in Visual Studio with the message “Object not set to an instance of an object”, after which nothing happens and my project was not added.

If you’re having the same problem try these steps:

1. Open Visual Studio Command Prompt
2. devenv /resetskippkgs [return]
3. Close VS
4. devenv /setup [return]
5. devenv [return]

Hopefully now you’ll be able to add a Silverlight project to your solution.

Source of this solution here.