Ok, before I say anything, I am going to say it now that I have ran a full Apple Diagnostics and there are 'No Troubles found' with my laptop. Couldn't be farther from the truth... And yes, I started a new thread. My old one was had too many posts and the guys that were helping me never came back. I couldn't wait any longer because I have only 30 days to return this hard drive and it has already been 15. Here's the jist: My hard drive died in my MBP a few days ago, so I went out and bought a new Western Digital 2.5" Scorpio 320 GB HD from Fry's. It even said on the side of the box it supported the Mac OS. So I install it, I install Mac OS X, and was then at the point were you are asked to Migrate any old data. I chose yes, intending to migrate my user account from my External Hard Drive. The HDD was not detected, so I said "Oh, Well" and hit Go Back. The pinwheel replaced the mouse and just sat there spinning. I let it sit for about a minute and a half before doing a Hard Shutdown. I rebooted the computer and watched the Apple Welcome Video for the 2nd time, only this time the video froze when the big X started flipping onto the screen. The audio continued, but the video was frozen. The computer seemed unresponsive. I let it sit for a minute before saying ****, and restarted for the third time. This time I get a kernel panic while the apple logo is on the white screen with the loading circle under it. Great. Then I booted from my External Hard Drive to see if the hard drive was still detected in Mac OS X. It was. At this point, I should have ran Disk Warrior or something, but I didn't. I ran a Verify from Disk Utility, which reported the drive to be a green 'OK'. I ran a Check Permissions, which froze Disk Utility half way through the test. I gave up for the night and shut off my laptop. Started it next morning, and then the disk was gone from the desktop and Disk Utility (including the install disk version). I am at a loss as to what I can do at this point. When the hard drive is not detected in any of my diagnostic programs, I can't get much accomplished. I can hear the HD running, so I know it has power. I thought maybe I should unplug it from the logic board, and plug it back in. But I did not have much faith that it would solve the problem, so I have not done that yet. I wish I did not have the only Macbook to date that does not have a conveniently accessible hard drive next to the battery. I have to take the damn top case off every time I want to do anything to the hard drive. Any suggestions on how to get the hd recognized? I find it hard to believe the hard drive could possibly be completely useless now, but I have no idea. After a few replies, here is what came next: Ok, I installed a replacement of the exact same hard drive, and I can hear it humming. But it does not seem to be detected at all. I can't format it because of that. I am back to the System Profiler 'there was an error scanning for Serial-ATA devices' crap that I had with the hard drive that failed during the OS X install. I know there is nothing wrong with the SATA controller because it is detected and reported as working without the hard drive plugged in. I haven't tried to format it or anything yet, because it is not detected in Leopard Installer. What the Hell !?!? Reply Update: Reopened the case and checked the connections, still isn't detected, yet I can hear and feel it spinning up and running... And there is nothing wrong with the ribbon cable connection or the front and keyboard lights wouldn't be working right now... Here is what I have thought to try, and will do so this weekend: I have an external 2.5" enclosure, so I will try to get the hard drive recognized with that. If I can, I will format it and hopefully then the comp will recognize it internally. If it does not mount in the enclosure, either, then maybe I am an EXTREMELY unlucky person and will go run and get a third replacement. If I am able to format it from the enclosure but the comp will won't recognize it internally, I don't know what do do about it. Diagnostics detects no problems, even with the unrecognized hard drive plugged in. System Profiler reports it as working as long as no HD is plugged in. Another thing I could try is to plug in my Seagate HD from my PS3 and see if it is recognized at all. If it is, than I can conclude that the WD Scorpio line of HD's just doesn't work with my computer and I need to buy something else. Too bad WD is the only brand that my local Fry's carries. Any help at all guys? BTW here is the other thread for reference: http://forums.macrumors.com/showthread.php?p=6925058#post6925058 I realize this is an extremely long post, but it is all necessary information. Thanks everyone and anyone in advance for any help they can toss at me. EDIT: Have the HD in an external USB case and it is now recognized correctly in Disk Utility. I will attempt to format it, and hopefully after I format it, the computer will recognize the hard drive internally.