Judging by the fact that you had problems with .NET Framework at the beginning, your problems are probably still connected to its installation. I checked to see and even running the launcher directly from the RAR archive allows it to work, so it's probably not the case.
Most versions of the .NET Framework are not cumulative, that means that installing 4.0 version only helps with program targeting the 4.0 version (from Microsoft's website: "The .NET Framework 4 works side by side with older Framework versions. Applications that are based on earlier versions of the Framework will continue to run on the version targeted by default."). The launcher is targeting the older version, 2.0, to make it more compatible as it doesn't use any new 3.0/3.5/4.0 .NET features.
I guess that .NET 2.0 is not properly installed because you should have received more informative
.