xboxhdm2.2 is working again
I changed the bootloader back to grub4dos (I assume the frequent updates to remprep_usb knocked out the bootloader).
FreeDOS is working again. Heres what it looks like now (ugly but working!)

I used the same customised C & E & it booted 1st time with no errors & no truncated files. See below

I also easily locked & unlocked with hdparm/hdm tools - no problems.
I also unlocked with master passwords on atapwd too - no problems
Note:
I consider this working release a final personal build & will not be supporting it.
I will get the 1st post updated in due course.
Download here (156mb): http://ge.tt/8p5Sw69?cquick install notes:
1. Extract zipped files to the root of USB stick
2. Populate the /hdm/C folder with the M$ Dashboard files.
3. Populate the /hdm/E folder with any chosen files (games saves etc) that you require installed.
4. Add the eeprom to /eeprom if you intend to un/lock
5.
Follow these instructions to install the MBR to get your USB drive to multiboot (**make sure you select the right drive to install the MBR to. Get it wrong and you could brick your PC!)
This post has been edited by scullc: Oct 24 2011, 10:30 AM