title: Magento export to CSV File shows "Error 503"
body: <p>Good morning.</p>
  
  <p>I've been having this issue for some days and have been lokking for a solution, but I haven't found one yet.</p>
  
  <p>The problem is, I have this Magento store and some grids can be exported to CSV files, while others shows:
  Error 503 Service Unavailable</p>
  
  <p>Service Unavailable</p>
  
  <p>Guru Meditation:</p>
  
  <p>XID: 853411302</p>
  
  <hr>
  
  <p>Varnish cache server</p>
  
  <p>The Magento version I'm using is 1.6.2. I guess the problem is not about PHP code, since the error shown is this generic error, instead of a PHP one (I even found the code used for exporting files and it seems to be ok).
  I would like to know why is this error being showed to me.</p>