title: IIS 7 Service Unavailable 503 ERROR
body: <p>I am encountering a 503 - Service Unavailable error. I checked the event log and found this:</p>
  
  <blockquote>
    <p>The Module name FastCgiModule path
    C:\WINDOWS\System32\inetsrv\iisfcgi.dll
    returned an error from registration. 
    The data is the error.</p>
  </blockquote>
  
  <p>Note: Every time I try to visit my website, I found that the DefaultAppPool will auto-stop.
  And also found this in event log:</p>
  
  <blockquote>
    <p>Application pool 'DefaultAppPool' is
    being automatically disabled due to a
    series of failures in the process(es)
    serving that application pool.</p>
  </blockquote>