Member Avatar for aaronsmom89

Hello All,

First of all, let me say that I really don't know much about computers, but I want to try to fix mine without just trashing it.

My husband was downloading a new poker site and he got a blue screen that said" the windows logon prosess system terminated unexpectedly. Fatal System Error Stop: C000021a."

The operating system is Windows XP. The computer is a Dell Dimension 2400. We are unable to access anything on the computer. This is the only screen that we can get to. The only way to restart the computer is to manually turn it on and off using the power button.

As a novice, is there anything that I can do?

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  • Latest Post Latest Post by caperjack

Dani AI

Generated

The stop code C000021A means a critical Windows user‑mode process (usually the logon subsystem or a core system process) has failed. That can be triggered by a bad install, driver or system‑file corruption, malware, or a failing disk. As pointed out, the usual Windows repair attempts are common first steps, but when irreplaceable photos are at stake a safer, data‑first approach is better.

A safe, non‑destructive recovery plan (in order of risk):

  • Avoid any further repair or reinstall attempts that write to the original drive until files are copied off.
  • If comfortable removing the drive: use a USB‑to‑IDE/SATA adapter or a powered external enclosure to attach the drive to a working computer and copy the picture folders to another drive. Older Dimension 2400 machines often use the legacy IDE/PATA connector, so match the adapter type.
  • If not removing the drive: boot the PC from a Linux live USB (runs entirely from RAM) and use its file manager to mount the Windows volume read‑only and copy pictures to an external USB disk. This bypasses the damaged Windows install without modifying the drive.
  • If the drive shows physical failure symptoms (clicking, unusual noises, repeated spin up/down), stop and consult a professional data‑recovery service — continued power cycles make recovery harder.

Notes and practical items:

  • Typical XP picture locations: C:\Documents and Settings\<username>\My Documents\My Pictures (also check Desktop and My Documents).
  • If the drive is readable but reports errors, create a full image (to another large disk) and run recovery from the image rather than the original; imaging preserves the original if recovery attempts go wrong. Tools for imaging and file recovery exist for both Windows and Linux; choose read‑only options where available.
  • Once the photos are safely backed up, proceed with Windows repair or reinstall steps to restore the system.

This preserves the best chance of recovering photos before attempting any repairs that modify the original disk.

Recommended Answers

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Member Avatar for caperjack

First try this ---press f8 during startup before the winlogo comes up, and choose "last configuration

If that does nothing ,then try this ,boot computer to you winxp cd ,choose "R" for repair ,pick 1 as the drive to fix ,just hit enter if it asks for a password, then type in "chkdsk /r" with out the quotes and there is a space between the K and /

Member Avatar for aaronsmom89

Thanks so much for the reply. I tried f8 and ended back at the blue screen.

What does this mean "boot computer to you winxp cd"? Do I put the cd in and then start the computer? (edited to add - I put the disk in and then started the computer and it looked like the computer was reading the disk, then the blue screen came up.)

Also, my mother in law was going to replace her computer anyway and gave us her old one. Hers is older than ours. Would it make any sense to take her Hard drive out and put it in ours? Is this something I could do?

I would rather try to save mine. All of my photos were on there.

Member Avatar for caperjack

hello ,yes it meant to put the winxp cd in the drive and restart computer ,you should see on the screen "hit any key to boot from cdrom " if you don't then you need to go into the bios and change the boot sequent to first boot cdrom .you inlaws harddrive will also give you the blue screen because of driver conflicts between the two different motherboards ,but you could put you harddrive in heres as a SLAVE and take you pictures off ,onto heres ,then reload winxp on you to get rid of blue screen .
Time for you to seek out the neighborhood computer geek for help ,every neighborhood has one or two !!

Member Avatar for emmtqg

First try this ---press f8 during startup before the winlogo comes up, and choose "last configuration

Thanks for your post - you saved me an indeterminant amount of downtime :)

Member Avatar for caperjack

Thanks for your post - you saved me an indeterminant amount of downtime :)

your welcome ,your lucky it doesn't work for a lot of people

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