I am running Windows 7 64 and I am use Visual C++ 2010 Express and when I try and load a project I get the error:
The C++ project "MyProject" is targeting ".NETFramework,Version=v4.0" which is not installed on this machine. You must download this framework, as well as .NET Framework 3.5, in order to open and build this project.
I have reset my computer, installed the framework, installed older version of the framework, tried editing out that line in the code, tried editing the line to match the version number and have had no success.
After a quick google search, I've ran into many possible causes and solutions. Since I don't know the problem personally (I dont use .NET), all I can do is direct you.