I formatted my harddrive about two nights ago. I took my harddrive (80GB Maxtor) out of my main computer and out it in my other one. My secondary PC was running XP Pro aswell. I formatted via CMD then: Format D: /fs:ntfs . Asked me to open handles or somthing or rather so I did. Then it formatted and I then installed XP Pro. All went swell and it booted up. However, it would only boot up if it was with my other harddrive, The option to choose which XP to boot off comes up and both work. When I take out my freshly installed XP on my 80GB and set it to master on either computer I get INVALID BOOT DI SK - oh joy. I've reformatted on my secondary computer 2 more times, tried install PRO again, I then tried just regular XP Home, no luck either time. I then tried formatting it on my main computer and trying XP home on that. No luck. I've tried setting the jumper settings on my harddrive differently, no luck. Plus if my computer worked prior dosen't seem logical that they would need to be moved. Anyway, there back to default now. I have tried setting the main 80 GB to master on both CPU's as well AS slave. Both alone and with the accompanying harddrive. It only works with the other one. =/ I've tried booting the XP disk and going into Recovery mode, I tried 'Fixmbr and fixboot' both completed sucsessfully but did not fix the problem. Then this morning, one of the prongs (the little gold pins that fit in the IDE cables) the last one on the bottom right... or maybe left broke off. Just one though. However it hasn't seemed to effect it so far. It still craps out when when alone, and still works fine when in company. I'm about ready to head to Best Buy and get one of their crappy 40gb 8mb buffer harddrives. Since I know that the 80 will work when it has a buddy. Any ideas would be appriecated. Thanks.