Thanks for the response. I "solved" the problem with a BIOS change which doesn't make complete sense to me.
I'm using an AMI BIOS. Under "Integrated Peripherals" settings I had
- Onboard Sata Controller [Enabled]
- Onboard Sata Mode [AHCI]
which is the way the computer came & is the default.
Windows has always seen the sata (HDD, DVD) as scsi.
When I change the onboard sata mode to [native IDE] windows sees the devices as ATA and Hirens bootCD, SeaTools now work.
Also, if anything the HDD speed has improved a bit.
I would have thought [AHCI] was the correct setting.