If you ever have a Visual Studio Server Explorer entry for a database that will not delete, you can manually go remove it from the xml file that contains those nodes.

We recently ran into this problem in Visual Studio 2010 were a SQL Server database entry would simply never delete. Attempting to delete it, or even open it, resulting in a string is not present in the dictionary error from Visual Studio that was annoying vague (what dictionary, and from what app).

Editing the DefaultView.SEView

The solution is to visit the VisualStudio directory for your users appdata and edit the DefaultView.SEView file that is found in that directory.

Directory: %appdata%\Roaming\Microsoft\VisualStudio\10.0\ServerExplorer\

The %appdata% directory can be browsed in the Windows Explorer, but you have to enter it by itself (entering the complete string above will fail to parse). Just putting in %appdata% will take you to your current users appdata folder. Then you can navigate down the rest of the path. The 10.0 is for Visual Studio 2010, 9.0 for Visual Studio 2008.

Filename: DefaultView.SEView

The file is really just an XML file. Find the offending entry and remove the complete <a1></a1> tag from the file. Save it, and restart Visual Studio - the node is now gone.