Trying to deliver fresh, active content through Active Server Pages can be a real challenge. Browsers and some proxy server insist on caching older versions of your pages. You made need a “shotgun” approach to handle all of the situations in which your ASP content can get cached. Try putting this combo at the top of your ASP pages. It is supposed to handle 4.0 browsers, proxy servers and Internet Explorer 5.
<%Response.Expires=0Response.AddHeader "Pragma","no-cache"Response.AddHeader "cache-control", "no-store"Response.ExpiresAbsolute=now()-1%>