Long crystal reports HTTP 404 error but gets generated after refreshing 2-3 times

Hi,

   I am running into a problem where the report takes 3-4 minutes to run directly on the CR server in infoview.The report gets generated correctly when you run it directly on the CR server.When I call the same report from the browser it times out giving me HTTP 404 error .After hitting the refresh button 2-3 times ,the report gets generated.We are using websphere and the session timeout has been set  to 60 minutes.The report uses 3 subreports to get the values

The same report gets generated when both the websphere and the CR server (2011) is on the same box.But when they are in different boxes,the report times out when it takes 3-4 mintes to run.I have checked all the timeout configuration in the Crystal Report Server and all of them have timeouts more than 10 minutes.

Any idea?

Thanks

Swagata