Windows STOP error 0x0000007B (inaccessable boot device) means that the OS cannot find a suitable driver for the disk drive you are trying to boot.
This can be caused by changing the SATA mode of your hard drive in the BIOS screen from AHCI to RAID.
The reason is that Windows 7 and Vista disable any drivers not currently in use to minimise start-up time so you will need to enable the new driver type before changing the BIOS setting.
Step 1) Go into the BIOS and change the SATA mode back to its previous (working) setting
Step 2) Boot into Windows
Step 3) Press Windows Key + R to open the "Run" dialog box
Step 4) Type "regedit" (without quotes) and hit enter
Step 5) Locate the key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV and set value to 0
Step 6) Locate the key  HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci and set value to 0
Step 7) Quit regedit
Step 8) Reboot your PC, enter the BIOS, and you can now change the SATA disk type to RAID or non-RAID to match your hardware setup.