IE9 deletes stuff
Please see <a href="http://blogs.msdn.com/b/ieinternals/archive/2011/08/19/understanding-the-impact-of-redirect-response-status-codes-on-http-methods-like-head-get-post-and-delete.aspx" rel="nofollow">http://blogs.msdn.com/b/ieinternals/archive/2011/08/19/under...</a> for a complete discussion of behavior.