Windows XP Won’t Boot After Windows 2000 Installed

If you install Windows 2000 after Windows XP and they are sharing the boot partition (i.e. C:) then you will receive an error message when trying to boot Windows XP.

Starting Windows...
Windows 2000 could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM.

You can attempt to repair this file by starting Windows 2000 Setup using the original Setup floppy disk or CD-ROM.
Select 'R' at the first screen to start repair.

--OR-- You may receive:

BAD_SYSTEM_CONFIG_INFO
STOP 0x00000074

To correct this, copy the Windows XP version of NTLDR and NTDETECT.COM to the root of the boot partition (i.e. C:\).  These two files need to replace the Windows 2000 versions.  You can find these files in the I386 directory on the XP CD or (possibly) in the Windows XP partition.