title: What could be the cause for error 1001 when installing my C# .Net application?
body: <p>I faced an error 1001 when I was trying to test installing the new version of my Windows application:</p>
  
  <pre><code>Error 1001 . An Exception occurred during the commit phase of the installation. This exception will        
  be ignored and installation will continue. However , the application might not function correctly 
  after installation is complete --&gt; Could not load file or assembly 'Microsoft.Win32.TaskScheduler, 
  Version=1.8.3.15820,Culture=neutural,PublicKeyToke...
  </code></pre>
  
  <p>This error only occurs when an old version of this application is in system. If I delete the old version, this installation will run fine.</p>
  
  <p>I just took over this project and I am new to C# .Net. I really have no clue what happened. I searched and I only found someone got this error when he was installing windows services. </p>
  
  <p>What could possibly cause this problem? Can anyone point out a direction for me to follow? </p>
  
  <p>Thanks!</p>