XBAP WPF Application Unable to Access Settings Within app.config

I have an XBAP WPF application that has been working for some time now. I am recently having problems accessing settings within the app.config.

Direct references to AppSetti开发者_JAVA技巧ngs return empty strings, and System.Configuration.ConfigurationManager.AppSettings.Count returns 0. Also, when trying to access a web service reference I get a "Could not find default endpoint element that references contract" error.

The app.config is copied to app.exe.config when running the application and there do not appear to be any differences.

Is anyone aware of any reason this might happen? The only change is that I have recently upgraded to a Windows 7 machine. Could I be missing a component? A colleague has run the same application on his machine with the same operating system with no problems.

Thanks.