I'm working with aVS 2005 windows project. When I try to add a database to the Server Explorer, I get the following Error message: "Key not valid for use in specifed state".I really appreciate your help as I can't go forward without this. Thank you.

It is a known issue with solutions in the links below. Hope this helps.

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=199339&SiteID=1

http://community.sgdotnet.org/blogs/darenhan/archive/2007/01/19/Key-not-valid-for-use-in-specified-state-in-VS-2005-database-project.aspx

It is a known issue with solutions in the links below. Hope this helps.

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=199339&SiteID=1

http://community.sgdotnet.org/blogs/darenhan/archive/2007/01/19/Key-not-valid-for-use-in-specified-state-in-VS-2005-database-project.aspx

Thank you, thank you! The answer was as easy as deleting a previous existing data connection.

(I had already deleted the "DefaultView.SEView" file -- I'm not sure if I needed to do that.)

I had the same problem in vb.express.  I went to the tools menu > connect to database.  I deleted all the connections.  I saved my project and closed it.  Opened again, and it works fine.