My mother had somehow managed to corrupt her HD on her older model gateway computer. The CD-Rom was not functional on her computer. I took the HD out of her computer and hooked it up to my computer under the "slave" jumper configuration. I reformatted the HD, installed, and updated Windows XP Pro. (just windows updated no drivers or anything) Windows was running flawlessly. I then removed the HD from my computer and returned the jumper settings to the way I found it. I put the HD back into my mothers computer. Everytime it boots up it says NTFS missing. I messed with the jumper a lot till it finally came up with operating system not found. I also tried all available IDE cable configurations. Any ideas on what the problem could be?