Solution to 'DotNetNuke unavailable' when using vs.net open DotNetNuke.sln

Want to display DotNetNuke in Visual Studio.NET 2003,got a error as below:
"unable to open Project file from web server,maybe web component is absent
 from visual studio.NET"
In solution resource manager of vs.net,word of 'unavailable' is right beside
to project name'DotNetNuke'
In process of correction,i tried to reinstall web developping component for
vs.net,but it didn't work.
By the hint of DotNetNuke.sln openned in NotePad,I changed virtual directory
name of 'dnn' to 'DotNetNuke' in IIS and solved the problem.