While trying to run the sample project ShellObjectWatcherSampleWPF from the latest version of Windows API Code Pack , I came across the following problem, both in Visual Studio 2008 and 2010: Or in a search-engine friendly way: “Cannot create instance of ‘MainWindow’ defined in assembly, ‘ShellObjectWatcherSampleWPF, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null’. Exception has been thrown by the target of an invocation. Error in markup file ‘MainWindow.xaml’ Line 1 Position 9.” Checking...