I recently purchased the WD6400AAKS SATA hard drive for my Compaq S5000NX system running Windows XP Pro, because Windows would give me messages saying "Error Loading OS" or "Operating System Not Found" when I booted up. I figured the hard drive was on its way out so buying a new one would fix my OS Error problem. Although that system supports IDE hard drives rather than SATA, I got a very good deal on the drive and couldn't pass it up. I found a SATA to IDE converter that attaches directly to the back of the drive and it works fine. Before I purchased this drive, I was running 3 hard drives total, a 40 Gig Western Digital as my main boot drive, a 160 Gig Western Digital and a 120 Gig Segate, both as slave drives, with a Sony DVD Burner. My problem starts here. When I boot up my system on just my 120 Gig Segate Drive with Windows on it, everything works fine. I can access the BIO's and it shows that the drive is present, etc. I then reboot my system and attach my newly purchased 640 Gig Western Digital drive as a slave to my 120 Gig Segate Drive running Windows, as well as my 160 Gig and my DVD-ROM. All have the correct master/slave settings. Everything works perfect when I boot up, I can access files, move them anywhere, etc. As soon as I restart the computer, or shut it down, it gives me an error saying "Error Loading OS" on my next boot. I hit ctr-alt-del to restart, and get the same message, over and over. If I unplug those 3 IDE drives (640, 160, DVD) and just run the 120 Gig (Which is my "Windows" drive) It runs perfect, except no drives are available, obviously. I then shut it off and re-attach the 3 IDE drives and it boots up perfect once again. But as soon as I restart/shutdown Windows, I get the Error Loading Os Black screen. I've tried just about everything I can think about besides replacing the motherboard/ram. I've switched out power supplies, used different IDE cables, reformatted all drives including putting a fresh copy of XP on the boot drive, tried setting all the drives to cable select rather than selecting slave/master, unplugged all the PCI cards, reinstalled drivers, updated the BIO's. I'm at the point where I just don't understand why it runs fine one time and as soon as you restart, it gives me the error message. I appreciate you taking time reading this and hope I explained everything in the correct fashion.
Edited by bodeche, 03 December 2008 - 10:46 PM.