Session timeout causes error page (yellow page of death) even though we have error page - SiteMinder Agent is used for authentication

Hi All,

We are using SiteMinder Agent for authentication and in the web.config of our asp.net we have implemented the error page as well as session timeout =20
but after the session time out the application goes to yellow page of death(Error page).
Server Error in '/' Application.
Runtime Error
Description: An exception occurred while processing your request.Additionally ,another exception occurred while executing the custom error page for the first exception.The request has been terminated
How to redirect the application to home page after the session timeout ?