Crystal Report doesn't show after some time

If application is in live environment and built using .Net Framework 4.0 along with SQL Server 2008 R2 database. Sometimes problem is rising when crystal report viewer doesn't able to show me on page. No matter how many times you reset iis server or clear sessions. Another weird thing that other pages behave fine with tables from which crystal reports pick the data working perfectly while crystal report doesn't.

One important link to resolve that issue is mentioned below.

http://forums.asp.net/t/1559602.aspx/1?Report+doesn+t+show+after+some+time

Sometimes this link will not help certain peoples, they also mentioned error "Report Load Failed", but if Exception is raising from method means its something is cooking there weird but why that exception not raised when any user hit different reports several time???

The simple solution for above mention issues are :

1. Please make sure the crsytal report version that you used on your code MATCHES the one you instal on the server.
2. Please make sure the crsytal report assemblies that you used on your code MATCHES the one you instal on the server.
3. Please make sure you allow FULL TRUST mode on your site/application.
4. Please make sure you set the application pool to run under LOCAL SERVICE permission.
5. Please make sure you copy the crystalreportviewer folder to your working folder.
6. Please make sure your server has enough RAMs to run Crystal Report.