Refresh warning

On my web form I have button that opens a crystal report (PDA format) in a separate window that looks similiar to a pop-up. When the user is finish they close the browser and the calling page displays the warning below. I see the warning go up right after I open the report. How can I prevent the following error? or extend the time for this warning to occur?

Warning: Page has Expired The page you requested was created using information you submitted in a form. This page is no longer available. As a security precaution, Internet Explorer does not automatically resubmit your information for you.

To resubmit your information and view this Web page, click the Refresh button.


Thanks,

James