You need to modify registry first, then change BIOS setting.
1. Click Start, type regedit in the Start Search box, and then press ENTER.
2. If you receive the User Account Control dialog box, click Continue.
3. Locate and then click the following registry subkey:
4. In the right pane, right-click Start in the Name column, and then click Modify.
5. In the Value data box, type 0, and then click OK.
6. On the File menu, click Exit to close Registry Editor.
Please Note: Please backup your registry before modifying it. For more detail steps, please visit the following link:
KB322756 How to back up and restore the registry in Windows (http://support.microsoft.com/kb/322756/)
Also, you can find more information about above steps in the following Microsoft Knowledge Base article:
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"
Hope it helps.
- Proposed as answer by Exiton Saturday, July 16, 2011 8:01 PM
All that happened was the Microsoft boot screen. Left for over an hour nothing. Doesn't the atapi Start need an non-zero (0) number such as 4 which the msahci had. And since the upgrade was installed from XP which requires an IDE Bios, wasn't the msahci driver not installed? If this is the case how does one install the driver?
Hope the following links can help you:
Error message when you update the SATA controller driver to the MSAHCI driver after you install Windows Vista Service Pack 1: "STOP 0x7B"
In addition, you also can check out the 5th post on this thread:
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
I want to change the SATA drives from IDE to ACHI in bios. When XP PRO 64 was upgrade to Ultimate 64 the atapi drivers were installed because the BIOS had SATA=IDE because of XP. Now I want to change Ultimate to boot from ACHI which unlike XP it supports. I have used regedit to change HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci\Start Value to zero (0) as is ...\Services\atapi\Start. When I re-booted the computer and change the BIOS to AHCI for SATA, the Microsoft stat screen came on and that's all. Waited for over an hour just the Microsoft progress bar. Re-boot an change the BIOS back to IDE and booted OK.
Using Cmd Prompt: sc qc atapi I get START_TYPE: 0 BOOT_START. I also get the same for sc qc msahci.
Should not the atapi\Start Value be equal to an non zero number such as 4 which what the \Start value was before I modified it?