I have installed Visual Studio 2012 Professional on my machine. I don\'t have Visual Studio 2010 installed, but I want to keep developing my applications using .NET Framewor
After creating new a project, go to its properties (select your project in Solution Explorer then right click and select properties) and select the target framework!
I solved the problem doing these tasks:
You fixed your problem, but it's likely that .NET Framework 4 Targeting Pack (not to be confused with the .NET Framework itself) failed to install for some reason. Did you get a warning at the end of the Visual Studio installation? Either way, in the future, a repair install of Visual Studio 2012 should have fixed the problem (Add or Remove Programs -> Microsoft Visual Studio [Edition] 2012 -> Change -> Repair).
I think that your issue is probably some mishap with the installation of .NET Framework. I installed Visual Studio 2012 Beta and have all kind of troubles with compatibility between framework versions. The only remedy was reinstalling Visual Studio, including .NET Framework.
Check out How to: Target a Version of the .NET Framework (MSDN).