I have copied a whole project onto my PC, both into My Documents/Visual Studio and into inetpub/wwwroot, but when I try to open the project in Visual Studio, it tries to open just 1 file .vssproj and gives me error messages, like : "The project file cannot be loaded. The application for project ... is not installed.". What am I doing wrong?
Without telling the specific error you're getting it's hard to help, but I'm guessing the file paths in the project file are incorrect. Try creating a new project and manually adding the files and see if you get the same errors.
Without the specific error messages, it's tough to be sure, but if you have an entire solution from your source machine rather than just a single project, you may want to try copying that over instead.
As others have said, without knowing a specific error it's hard to help. However, the sln and csproj files are just text files, you can always just open them up in notepad and do a search and replace on any obvious path problems. It's often quicker than creating a new project and adding all the files / references.
If VS 2005 has not been upgraded to Service Pack 1 then a web application project (rather than a website) will give this error.