Windows

Most STOP errors are hardware issues. STOP messages are identified by an 8-digit hexadecimal number, but also commonly written in a shorthand notation; e.g., a STOP 0x0000000A may also be written Stop 0xA. Four additional 8-digit hex numbers may appear in parentheses, usually unique to your computer and the particular situation.
A critical service failed to initialize while starting the LastKnownGood control set. If this is the first time you have booted after installing new hardware, remove the hardware and boot again. Check the Hardware Compatibility List to verify that the hardware and its drivers are compatible with your version of Windows. If Windows is loaded and no new hardware has been installed, reboot with recovery options set to create a dump file. If the message recurs, press F8 and select the Last Known Good option when you reboot. If there is no Last Known Good configuration, try using the Emergency Repair Disk. Also, strangely enough, I had this error and traced it to a dodgy XP Home Edition CD (yes, original), go figure! Working as a techie, since XP came out, I have noticed some batches of CD's seem to "struggle" a bit more to install, making you think it's the CD drive or Hard Drive.
That said, in general, you should always install the most recent OS last. In this case, you should install Windows 2000 and then install Windows XP. Install Windows 2K first as the XP install will locate the 2K partition and will write its own boot loader. This boot loader will allow you to switch operating systems during boot up via a "Boot Loader" screen.

SYMPTOMS

The following STOP message may appear when you boot Windows NT:


STOP: 0x0000006F (0xC0000034,0x00000000,0x00000000,0x00000000)
Session3_Initialization_Failed
CAUSE
A file critical to system initialization, such as Smss.exe, may be missing or corrupted.
RESOLUTION
Use one of the following methods to restore a missing or corrupted file:


If the Windows Operating System is installed on a FAT partition, copy the initialization file to the %SystemRoot%\System32 directory.If Windows NT 3.51 or 4.0 is installed on an NTFS partition, reinstall Windows NT to a separate directory. Log on as the same user with the same permissions and copy the initialization file to the %SystemRoot%\System32 directory. If Windows 2000 is installed on an NTFS partition use the Recovery Console to replace system files. For instructions on relacing system files using the recovery console see:

229716 Description of WIndows 2000 Recovery Console