Yesterday i was facing problems and got the error saying object reference not set instance of object problem. I think the problem is of skip packages So the common workaround is to start visual studio using the devenv /resetskippkgs And if this also doesnot work for you then here is a very good post to help you do have a look at that. http://weblogs.asp.net/bradleyb/archive/2008/06/09/upgrading-to-silverlight-beta-2-and-visual-studio-2008-sp1-beta.aspx