OK, after 2 days of bashing my head up a wall with this, 5 mins after posting the questiong I find the solution.
If anyone is interested it's top do with the SATA AHCI config within the bios, if you put this back to ATA so it uses IDA emulation, it images fine. I'm guessing once this image is finished I'll have to put the setting back to AHCI so it'll boot correctly.
Thanks anyways folks.