You say the problem is intermittent, so you have to concentrate on troubleshooting the problem when it happens, not when it doesn't.

Are you saying that for these intermittent ones

1. The schedule is successful and there is NO error in the schedule history and the CRD error log and the Windows Event-Viewer logs?
2. In the CRD email log the email is NOT there?

When running the reports manually - I can see in the email log that they have ran properly.
however , the same reports are running but not being sent when set by schedules.

So we need to troubleshoot the scheduler, not your manual run.

So my questions again for when the scheduler runs those schedules:

1. The schedule is successful and there is NO error in the schedule history and the CRD error log and the Windows Event-Viewer logs?
2. In the CRD email log the email is NOT there?

Go to Options-Messaging and switch on "Retry failed Mails".

no error in event viewer , or in the error log of the CRD.

Error is sent as :
-----------------------------------------------------
PC Name: PX0022
Schedule Name (if applicable):
Date: 12/19/2007 1:28:20 AM
Error Description: [Microsoft][ODBC SQL Server Driver]Cannot initialize SSPI package
Error Number: -2147467259
Error Source: OpenMainDataConnection
Line Number: 0
-----------------------------------------------------

please advise

Happens if there is no connection to the sql database.

You need to find out what is happening to the connection to the sql database at that time that CRD was trying to connect to it and fix the problem. It is likely to be a network issue, or the database is off line, a backup program is running, the sql server is restarting or anything like that.

You can google the error "Cannot initialize SSPI package" to see more information and solutions.