title: What are the dangers of making a method virtual?
body: <p>I've been doing some mocking with RhinoMocks and it requires that mocked methods be made virtual. This is fine except we have a custom framework which contains the methods that I want to mock which are currently not marked as virtual.</p>
  
  <p>I can't forsee any problem with making these methods virtual but I was wondering what are some potential dangers of making methods virtual that I should look out for?</p>