title: Why does the message BC30560 'mymodule_ascx' is ambiguous in the namespace 'ASP' come up sometimes then go away?
body: <p>Often when making changes to a VS2008 ASP.net project we get a message like:</p>
  
  <p>BC30560: 'mymodule_ascx' is ambiguous in the namespace 'ASP'.</p>
  
  <p>This goes away after a recompile or sometimes just waiting 10 seconds and refreshing the page. </p>
  
  <p>Any way to get rid of it?</p>