But it won't let me extract anything, the button remains greyed out, even after choosing the right folder.

Wait a second... how do you know?

Got the same problem, .NET 3.5 is installed and checked in the Windows features list, though the debug messages says this: CodeBase: file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/mscorlib.dll So there's 4.0 for some reason. Any ideas on that? And unpacking gives me some weird files I honestl...