title: WPF window crashes on startup, or it starts but hangs and does not render contents
body: <p>I've had a couple nasty problems with WPF applications crashing on certain client machines but working everywhere else - every developer's nightmare.</p>
  
  <p>I'm posting the problems / solution here to help preserve the sanity of fellow developers. These were not easy to troubleshoot. </p>
  
  <p>Both of these issues are classic "it works on my machine but not theirs" issues.</p>
  
  <ol>
  <li>WPF app crashes on startup. No errors, no idea why. </li>
  <li>WPF app starts up, the window border shows, but the contents do not paint. It just hangs (reported as a "transparent window") Clicking to close triggers a crash report (machine was windows XP).</li>
  </ol>