Why I am getting a windows security Pop Up on accessing pages with in a report folder with aspx and rpt files in an asp.net application in IIS 7.5?

See more:

C#2.0

C#

ASP.NET

CrystalReports

, +

Why I am getting a windows security Pop Up on accessing pages with in a report folder with aspx and rpt files in an asp.net application in IIS 7.5?
All aspx pages under other folders and subfoldersare accessible.But for the report folder windows security window pops up and If the credentials are entered then on accessing those pages with in folder with issue, resource not found error comes. All other pages with in other folders are accessible and no windows security pop up comes. The site is accessed via internal ip address.We are using forms authentication mode and all users are allowed access under the authorization part in web.config. permissions are set for the report folder too. Crystal Report Version we are using is 10.2.3600.0

In web.config authentication and authorization tags are set as follows:

<authentication mode="Forms"> 
            <forms name="CLIAUTH" path="/" loginUrl="Login.aspx" protection="All" timeout="30"/>
        </authentication>

<authorization>
<allow users="*">