logoff problem, how to remove ReturnUrl after logoff?

I am using FormsAuthentication and when the user clicks log out then the page name of current page is appended to the ReturnUrl, just likes "Login.aspx?ReturnUrl=xxx.aspx". And then if a different user wants login, after he has been authenticated,he is also redirected to "xxx.aspx" that page. Any ideas to solve that? Thanks.



   Protected Sub btnLogOut_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnLogOut.Click

        FormsAuthentication.SignOut()
        Roles.DeleteCookie()
        FormsAuthentication.RedirectToLoginPage()

    End Sub


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