how can clear FireFox3+ version cache value through asp.net application.

Hi All,
 
i am using ADFS2.0 with Asp.net 3.5.i am creating one Asp.net Relying party application, within this Relying application i am using
one proteced page (modify.aspx) when i click browser back button from this page (modify.aspx) then it throw an error "A potentially dangerous Request.Form value was detected from the client (wresult="<t:RequestSecurityTo...")."
so i used validateRequest="false" on @page directive and this issue has been resolved.
but i am facing another issue now my master page is not load again when i press back button from this page (modify.aspx).
but i was accepting "web page expire" white out page error.
so i am trying to clear browser cache  value through below code
HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
HttpContext.Current.Response.Cache.SetNoStore();
and i have also try so ...