How can I step into Microsoft's .NET framework source code?

Question

I\'d like to step into Microsoft\'s source code but cannot.

I followed the instructions at Configuring Visual Studio for Debugging. In particular, I disable

Answer 1

Not all parts of the .NET framework is available as reference source, but the parts that are (and steps for getting it up and running) is described in Shawn Burke's blog, Configuring Visual Studio to Debug .NET Framework Source Code.

Update: Hmm. It is broken on my machine too although it used to work. Weird.