Installation of the Microsoft Dynamics CRM Reporting Extensions formally known as the SSRS Data Connector (Still in on the installation media in same folder) is necessary so that CRM and SQL servers can communicate over the kerboros double hop issue when using to seperate servers.
This key is the word ITEM cannot be found. This simply means the SSRS data connector cannot find the original reports. It turns out the report databases that support SSRS were completely removed, disgarded when the SQL server was rebuilt, so the CRM reports were now missing. (Note: Custom Reports would have been deleted and cannot be restored using this procedure. A backup of the ReportDB\ReportTempDB would be required, with a repair of SSRS to get those reports working again).
In order to fix this, remove and reinstall Reporting Extensions first, then run the command line tool from the crm server directory C:\program files\Microsoft Dynamics CRM\Tools\ to recreate/republish the reports by typing the following command :
Once completed, issue an IISRESET on the crm server. Then navigate back into CRM report section and run/find your missing reports! There are several other topics covered on this blog around SPNs and Service Accounts that could also be an issue if your reports are not working. Take a look! Enjoy.