Sql Server Reporting Server 2008

Hi All,

My application is on Sharepoint Sever 3.0,asp.net 3.5 and using SSRS 2008 for reports. The reporting server was working fine but suddenly it started giving the following error

• An error occurred during client rendering.
  • An error has occurred during report processing. (rsProcessingAborted)
    • Cannot create a connection to data source 'dataSourceScreeningSummary'. (rsErrorOpeningConnection)
      • The ConnectionString property has not been initialized.                                                However when i view the report from "View Desinger" mode it works. Please Help... :)