How can I reconstruct this error?

<i><b>Originally posted by : warmfish (fengxu@wang.com.cn)</b></i><br /><br />When I build a window application or asp.net web application, the user interface always don't appear (example: form1.cs or index.aspx cant appear to design), and give me an error:<br /> An error occured while loading the document,fix the error,and try loading the document again,the error message follows:<br /> file or assembly name EnvDTE,or one of its dependencies,was not found!<br /><br /> How can I reconstruct it,can you tell me? thanks