Richard:
During the IDR CD image creation, the elxstor.sys driver found on the Windows 2003 SP2 installation media will be replaced with the elxstor.sys driver file collected from the system, on the resultant IDR .iso image.
It is possible that the elxstor.sys driver file collected from the system might be of older version, which refuses to load during a Windows 2003 SP2 boot.
You can comment the elxstor entry in the [PreLoad SCSI or RAID Drivers] section of your idr.sif configuration file ( found under <BE Install Path>\idr\disk4\idr.sif ) and try creating a new IDR CD image. To comment the entry in the idr.sif file, add a semicolon at the front of the line. i.e; change
[PreLoad SCSI or RAID Drivers]
...
...
elxstor = PCI\VEN_10DF&DEV_F0A1,PCI\VEN_10DF&DEV_F0D1,PCI\VEN_10DF&DEV_F0E1,PCI\VEN_10DF&DEV_F085,......
to
[PreLoad SCSI or RAID Drivers]
...
...
;elxstor = PCI\VEN_10DF&DEV_F0A1,PCI\VEN_10DF&DEV_F0D1,PCI\VEN_10DF&DEV_F0E1,PCI\VEN_10DF&DEV_F085,......
and try to create a new IDR CD image.