title: OpenFileDialog fails on WPF C# based app after install
body: <p>Strange issue with an app I'm helping on. </p>
  
  <p>App attributes:</p>
  
  <ul>
  <li>VS 2013</li>
  <li>.Net 4.0</li>
  <li>x86 target</li>
  <li>WPF / C# / MVVM using Prism</li>
  <li>key library: SlimDx</li>
  </ul>
  
  <p>We are using the setup/installer extension noted here:</p>
  
  <p><a href="https://stackoverflow.com/questions/20351947/create-an-application-setup-in-visual-studio-2013">Create an application setup in visual studio 2013</a></p>
  
  <p>Our first install/setup attempt has tested fine with a developer centric Win8.1 x64 laptop and a normal Win10 laptop install.</p>
  
  <p>However, on a nearly virgin Win8.1x64 install, we found a couple of strange issues.</p>
  
  <p>1) The custom file associations failed to apply (worked on other install tests). For some reason our *.custom is associated with Notepad on this unit. No errors were noted during installation.</p>
  
  <p>2) The File-Open dialog (using  Microsoft.Win32.OpenFileDialog) fails to show any <em>.custom</em> files in the desired Filter settings. The file type names are properly listed by the dialog filter drop box, but they do not show the "(*.custom)" filter next to the names nor does the dialog list the files that are known to be present. All of this works fine on other installs. This prevents the app from opening the desired files.</p>
  
  <p>Being primarily an embedded software/firmware developer, not sure how to debug such an issue.</p>
  
  <p>So, the primary question is: what would cause the above behavior?</p>
  
  <p>Secondary question: what are best practices for debugging post-install issues like this? (perhaps I need to ask this as another question...)</p>
  
  <p>Thank you very much,</p>