WPF Application fails on startup with TypeInitializationException

Question

I have a simple WPF application which I am trying to start. I am following the Microsoft Patterns and Practices \"Composite Application Guidance for WPF\". I\'ve followed

Answer 1

Thanks @ima, your answer pointed me in the right direction. I was using an app.config file and it contained this:

It seems the problem was the element because when I removed it the application ran fine. I was confused because Visual Studio 2008 added that when I checked the box to utilise the "Client Profile" available in 3.5 SP1.

After some mucking about checking and un-checking the box I ended up with a configuration file like this:

Which works!

I'm not sure why the order of elements in the app.config is important - but it seems it is.