Issue with IE 6.0 caching

Hi,
I am using the following settings to disable caching over a secure connection

         Response.Expires = -1500;
         Response.Cache.SetNoStore() ;
         Response.Cache.SetCacheability(HttpCacheability.NoCache);
         Response.AppendHeader("Pragma", "no-cache");   
IIS is set to use GZip compression.

Inspite of these settings, IE6 is caching the server's response and when I hit the browser back button, I see the view secure and non secure items message. The message disappears if I clear the cache. This is causing a bug in my app when using IE6. It works fine with other browsers (including IE7). Am I doing something wrong? How do I force IE6 to not cache?
 Thanks in advance.
 
 

 &nb ...