This option is to try to solve the problem that sometimes occurs with improper installation of Microsoft .NET Framework. Therefore, you must go to Control Panel and find the option to install-uninstall programs comprobra if you have the following installed versions:
Microsoft .NET Framework 2.0
Microsoft .NET Framework 3.5
Microsoft .NET Framework 4.0
If you lack any of them need to install *, if you already have some of them, I would recommend that come back to install (* the version are compatible and therefore can be both on your computer without involving a problem).