Please help me with the ASP.NET return URL

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C#

C#4.0

ASP.NET4

I am creating an ASP.NET application, everything is working perfectly well but with little probs, the session has been define to expire
after 30 minutes in the web.config file, for other pages on the page when the expire expires while on the page the formsauthentication will redirect the user to the login page and after successful login the user is redirected back to the Return URL, but there is this page that can only be accessed if a particular patient information is availaible and so it has some query string values that (4 to 5 query string value)
but when on this page and the session expires, after successful login the user is not redirect back to that page but the page displays an error stating (The return URL specified for request redirection is invalid.)