By the sound of your posts, it sounds like the hard drive is locked while you're trying to access it with XboHDM. You have to let your xbox unlock it by loading up the MS Dashboard and letting it sit for a few seconds, at that time, you swap the IDE cables. If, at any time, power to the hard drive is lost, then the drive locks again. You can't just stick the hard drive in your computer, because it will be locked. You will always have to hotswap unless if it's a brand new hard drive or one that you have unlocked and disabled.