I dug this up at microsoft's technet site, hope it helps.
Stop 0x0000007B or INACCESSIBLE_BOOT_DEVICE
The Stop 0x7B message indicates that Windows XP Professional has lost access to the system partition or boot volume during the startup process. Installing incorrect device drivers when installing or upgrading storage adapter hardware typically causes stop 0x7B errors. Stop 0x7B errors could also indicate possible virus infection.
Interpreting the Message
This Stop message has four parameters:
The address of a Unicode string data structure representing the Advanced Reduced Instruction Set Computing (RISC) Computing (ARC) specification name of the device at which you attempted startup.
Pointer to ARC name string in memory.
This value is 0x00000000 (zero).
This value is 0x00000000 (zero).
The first parameter typically contains two separate pieces of data. For example, if the parameter is 0x00800020, 0x0020 is the actual length of the Unicode string and 0x0080 is the maximum ARC name string length. The next parameter contains the address of the buffer. This address is in system space, so the high-order bit is set.
If the file system is unable to mount the boot device or simply does not recognize the data on the boot device as a file system structure, the following parameter definition applies:
The address of the device object that could not be mounted.
Error code value or 0x00000000 (zero).
This value is 0x00000000 (zero).
This value is 0x00000000 (zero).
The value of the first parameter determines whether the parameter is a pointer to an ARC name string (ARC names are a generic method of identifying devices within the ARC environment) or a device object, because a Unicode string never has an odd number of bytes, and a device object always has a Type code of 0003.
The second parameter is very important because it can indicate whether the 0x7B Stop message was caused by file system issues or problems with storage hardware and drivers. Values of 0xC000034 or 0xC000000E typically indicate:
Disks or storage controllers that are failing, defective, or improperly configured.
Storage-related drivers or programs (tape management software, for example) that are not fully compatible with Windows XP Professional.
Resolving the Problem
The following suggestions are specific to Stop 0x7B errors. For additional troubleshooting suggestions that apply to all Stop errors, see "Stop Message Checklist" later in this appendix.
During I/O system initialization, the controller or driver for the startup device (typically the hard disk) might have failed to initialize the necessary hardware. File system initialization might have failed because of disk or controller failure, or because the file system did not recognize the data on the boot device.
Repartitioning disks, adding new disks, or upgrading to a new disk controller might cause the information in the Boot.ini file, or Boot Manager, to become outdated. If this Stop message occurs after installing new disks to your system, edit the Boot.ini file or adjust the Boot Manager parameters to allow the system to start. If the error occurs after upgrading the disk controller, verify that the new hardware is functioning and correctly configured. For more information about the Boot.ini file, see "Troubleshooting Startup" in this book.
Verify that the system firmware and disk controller BIOS settings are correct and that the storage device was properly installed. If you are unsure, consult your computer's documentation about restoring default firmware settings or configuring your system to auto-detect settings. If the error occurs during Windows XP Professional setup, the problem might be due to unsupported disk controller hardware. In some cases, drivers for new hardware are not in the Windows XP Professional Driver.cab library, and you need to provide additional drivers to complete the Windows XP Professional setup successfully. If this is the case, follow the hardware manufacturer's instructions when installing drivers. Periodically check for driver and firmware updates.
Hard disk corruption can also cause this Stop message. For more information about checking hard disk integrity, see the instructions provided in "Stop 0x00000024 or NTFS_FILE_SYSTEM" earlier in this appendix.
Problems that cause 0x7B errors might also cause Stop 0xED errors. For more information about 0xED Stop messages, see "Stop 0x0000007B or INACCESSIBLE_BOOT_DEVICE" later in this appendix.
For more information about Stop 0x7B messages, see the Microsoft Knowledge Base link on the Web Resources page at
http://www.microsoft.com/windows/reskits/webresources. Search using keywords winnt, 0x0000007B, 0x7B, and Txtsetup.oem.
