So i have found the numerous articles explaining using 2 pages and one controller to export data to a csv file. I have followed the steps and my created csv file always has the following code appended:

<script type="text/javascript">  SfdcApp.Visualforce.viewstate.ViewstateSender.sendViewstate('https://cs10.salesforce.com' 'ClientPortalCases');  </script>

how do i prevent this code from appearing?  I have seen other people mention this appearing but have never seen a solution.  I also tried exporting to xls but then you get the error message explaining that the extension and the file format don't match.  

Please help!