How to Change SATA Hard Disk Mode from IDE to AHCI / RAID in BIOS after Installing Windows?

If you are using Windows XP in new laptops or PCs, this article may help you. I got it from this link.

Consider following scenario:
You got a new computer system in which the SATA hard disk controller mode in BIOS settings was set to IDE ( or IDE Compatibility or Standard IDE) instead of AHCI (Advanced Host Controller Interface) or RAID for better compatibility. You didn't notice that and installed Windows. After sometime you realized it and changed the SATA mode from IDE to AHCI or RAID in BIOS and BOOM!!! You made your Windows crashed. Windows will no longer start and will show a BSOD (Blue Screen Of Death) containing error code "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE".

Why??? Because Windows can't load the new drivers for AHCI or RAID interface. Actually when Windows is installed, it automatically disables unused storage drivers to speed up Windows startup process.
As a temporary fix, you can reset the SATA mode from AHCI or RAID to IDE in BIOS but you'll find yourself in the same situation. Or you can reinstall Windows but that would require lots of time and efforts.
Then how to switch SATA hard disk mode from IDE to AHCI or RAID in BIOS after installing Windows so that you would not need to repair or reinstall Windows?
Here is the solution! You just need to tell Windows that hard disk mode is going to change upon reboot using Windows Registry and Windows will automatically detect the mode and will install the required drivers and you'll be able to successfully change the SATA mode in BIOS without any need to reinstall Windows.
So without wasting time lets start the tutorial:
1. First DO NOT change SATA hard disk mode settings in BIOS, leave it to the default settings which were used while installing Windows.
2. Now start Windows and type regedit in RUN or Start Menu search box and press Enter. It'll open Registry Editor.
3. Now go to following keys one by one:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\msahci
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\pciide

In right-side pane, look for a DWORD "Start". Double-click on it and set its value to 0 (That's zero and not alphabet O).


4. If you are using RAID or other interface, do the same thing for following key as well:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStorV

In right-side pane, look for a DWORD "Start". Double-click on it and set its value to 0 (That's zero and not alphabet O).

5. That's it. It'll reset the hard disk mode settings in Windows registry. Close Registry Editor and restart your system.
6. Now enter into BIOS settings and change SATA hard disk mode to AHCI or RAID according to your requirements.

7. As soon as Windows will start booting, it'll automatically detect the change and will install the appropriate drivers. Once the drivers are installed, Windows will boot without any problem and you'll not need to reinstall Windows just to change SATA hard disk mode.