Section B: Troubleshooting hardware and system file based BSODs

Section B: Troubleshooting hardware and system file based BSODs If you can't even boot into safe mode without a stop message, and the 'last known good configuration' boot option did not help, it's likely you have a hardware or system file error. There's a procedure for each and neither is particularly fast, so we will run through the procedures in ascending order of difficulty.
Checking for hardware errors
First off, have you added any new hardware devices or peripherals to your system recently? If so, power off the computer and remove them, then attempt to boot again normally.
If you changed the motherboard in your system, or moved your Windows installation to a new system before the error occurred, you must perform a Repair Install before XP will work correctly again. See the section below entitled 'Fixing missing or corrupted system files.'
If you haven't added new devices recently, or if removing them does not solve the problem, it's time to test your system's memory.
Testing system memory
From another computer, obtain the Windows Memory diagnostic or Memtest memory diagnostic programs on floppy or CD, then use them to boot your system and test the memory. If either of these programs shows any errors in your memory, you have likely found the source of your troubles. Chances are you will need to purchase new memory.

Fixing missing or corrupted system files
Windows XP will often refuse to work if certain system files are missing or become corrupted through hard drive or virus issues. Likewise, changing the motherboard (or the entire system) under your Windows XP installation will stop it working until the system files are repaired and updated.
To do this, you should perform a Repair Install.
The repair install process reinstalls all Windows system files while leaving directories, settings and user data intact. This should fix any corrupted files that are causing BSODs and crash issues. To perform a repair install:

1. Boot from the Windows XP installation CD
2. Choose the 'press enter to set up Windows XP now' option
3. Press F8 to skip through the EULA
4. Now press R to begin a repair installation

Your system will go through the entire XP install process, but will not attempt to replace any of your existing data. It will simply reinstall the system files and redetect all hardware. Once the process has completed, your computer will reboot. Note that if you perform a repair install, you will need to visit the Windows Update Site and reload any patches and Service Packs that you previously applied to your system, as the repair install will remove them all.
Identifying other defective hardware
If you are still experiencing constant crashing, power off your computer again, open the case and remove all non-essential hardware. The only things still connected to the system and motherboard should be:
Mouse & keyboard
Hard drive
CD-Drive
Video card
Memory
(And obviously the processor and power supply must still be connected also)
If you are unsure of how to remove the parts correctly, or which is which, see our PC Assembly Guide here.
Now try booting the computer into safe mode first, then normally. If you can boot into Windows without a stop error, you can be sure the issue is with one of the peripherals you removed. Now you can pinpoint the problem by selectively reinstalling each component (with the power off) and restarting windows...