If you really enjoy tinkering with computers, you can just make the computer not boot! I recently played BIOS on my Windows 7 test block and after restarting my computer I got the following error message:
STOP 0x0000007B INACCESSABLE_BOOT_DEVICE
Luckily, I knew that it was something I changed in the BIOS that caused this issue. If your computer has SATA drives, you probably want to use the Advanced Host Controller Interface (AHCI) on your SATA host controller.
In the BIOS, you can usually choose which mode the SATA controllers should use, for example PATA (Parellel ATA), standard AHCI, or some kind of manufacturer-specific RAID.
If you go into BIOS and see that you are not using AHCI for your SATA drives and decide to switch to it for maximum performance and data transfer, you will likely get this error after trying to restart.
Basically, before you can switch to AHCI in BIOS, you need to enable the AHCI driver (msahci.sys) in Windows 7 or Windows Vista.
Ok, so the first thing to do in order to use AHCI is go back to BIOS and revert the mode back to the original setting you used so you can load a Windows backup.
Back in Windows, click Start, then type regedit in the search box and press Enter.
Now navigate to the next registry key in Windows 7:
HKEY_LOCAL_MACHINE System CurrentControlSet Services Msahci
Now right click on the Start button in the right pane and select Change. Change the value to 0 and click OK.
Now exit the registry and restart your computer. Go back to BIOS and re-enable AHCI mode for your SATA controller and you should be fine!
The reason this is happening is that by default, when installing Windows 7 or Windows Vista, all unused storage drivers are disabled to improve performance. To use them, you first need to enable the driver in the registry.
AHCI is better because it provides benefits such as hot-plug functionality, power management, and faster data access. Enjoy!