title: DefaultValueAttribute conflicts with XML serialization
body: <p>I am trying to let user modify an object before serializing it. For objects' editing I use PropertyGrid, so I have to add attributes to it like this:</p>
  
  <pre><code>    [CategoryAttribute("General"),
      DefaultValueAttribute(true),
      DescriptionAttribute("Calculate MD5")]
      public bool ComputeMd5 { get; set; }
  </code></pre>
  
  <p>When I try to serialize this object, property disappears, when I remove all properties, serialization goes through without any problems. Any idea why? </p>