Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows

To resolve this issue, enable the AHCI driver in the registry before you change the SATA mode of the boot drive. To do this, follow these steps:

Modified version guide:

1) Boot to Vista with AHCI Disable in the BIOS

2) Exit all Windows-based programs.

3) Click Start, type "regedit" in the Start Search box, and then press ENTER.

4) If you receive the User Account Control dialog box, click Continue.

5) Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci

6) In the right pane, right-click Start in the Name column, and then click Modify.

7) In the Value data box, type 0, and then click OK.

8) On the File menu, click Exit to close Registry Editor

9) Reboot and boot to the BIOS and set AHCI to Enable, save and exit.

ASI Notebook Alert ! - Enable Windows Vista AHCI driver to an existing Vista OS with out having to re-install Windows Vista

Article ID: 922976	September 17, 2007	http://support.microsoft.com/kb/922976

Error message when you start a Windows Vista-based computer after you change the SATA mode of the boot drive: "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE"

SYMPTOMS
Consider the following scenario. In the BIOS setup of a Microsoft Windows Vista-based computer, you change the Serial Advanced Technology Attachment (SATA) mode of the boot drive to use the Advanced Host Controller Interface (AHCI) specification. You then restart the computer. In this scenario, you receive the following error message: STOP 0x0000007B INACCESSABLE_BOOT_DEVICE

CAUSE
This issue occurs if the AHCI driver (Msahci.sys) in Windows Vista is disabled. This driver must be enabled before you change the SATA mode of the boot drive.

RESOLUTION
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows To resolve this issue, enable the AHCI driver in the registry before you change the SATA mode of the boot drive. To do this, follow these steps: Modified version guide: 1) Boot to Vista with AHCI Disable in the BIOS 2) Exit all Windows-based programs. 3) Click Start, type "regedit" in the Start Search box, and then press ENTER. 4) If you receive the User Account Control dialog box, click Continue. 5) Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci 6) In the right pane, right-click Start in the Name column, and then click Modify. 7) In the Value data box, type 0, and then click OK. 8) On the File menu, click Exit to close Registry Editor 9) Reboot and boot to the BIOS and set AHCI to Enable, save and exit.