QUOTE(Heimdall @ Apr 28 2009, 03:23 PM)

There's a thread on this somewhere with more detail, but there seem to be three possible ways to get round the BIOS freezing the drive:
1. Plug the disk into the IDE cable after the PC has booted. Make sure the disk is jumpered as master, not cable select.
2. Plug the disk into the IDE cable after POST but before the computer boots from the xboxhdm CD - use Pause-Break to suspend booting while you plug in the drive. Make sure the disk is jumpered as master, not cable select.
3. Set the BIOS to primary HD = none instead of autodetect.
You've already tried option 3, so try one of the others. As with all plugging of IDE cables on a live computer, there is a risk of damage, becaused IDE isn't designed for hotswapping.
Just FYI to the original poster, I have the same problem and have tried EVERY possible way of plugging / unplugging power / IDE cable to HD before / after post / boot / prior to entering menu item 3 / after entering menu item 3 / etc. None of the ways worked, and I'm lucky I haven't fried my new HD yet. And now I have stopped trying.
Going to just think for a few days. Trying to do this in a hurry will definitely mess things up. Right now I'm hitting all my friends for an old computer that supports IDE that I could borrow to lock the drive. Hoping I get lucky. Some day I hope to find a computer with a motherboard that just works.
I must say I'm surprised no one has posted a page that lists retail computers, motherboards, BIOSes that don't have this problem, given all the trouble people have gone through to help people with XBox's, this site included. I guess we are the only unlucky ones who's computers cannot lock the HD.
Wishing you the best.