When turned on it starts up through to opening operating system then shows blue screen reading the following STOP: c000021a {Fatal System Error} The Windows Logon Process system process terminated unexpectedly with a status of 0xc0000034 (0x00000000 0x00000000). The system has been shut down. can anyone help me get it back up and running ????

It appears that your Windows Registry is corrupted. You can try to use a Registry repair utility like CCleane to fix it. If that doesn't work you will have to reload Windows OS (Operating System). For more info no this error code Google "c000021a".

Click on my computer.
Right Click on the C: drive.
Choose Properties.
Tools tab.
Error checking: Check now.
Choose automaticly fix file system errors.
Start, Yes, OK, Reboot the PC.
On boot a blue screen will launch and run for 5 - 20 minutes.
It wll reboot into windows when completed.

This Microsoft article may be of help to you. http://support.microsoft.com/kb/317189

Blue Screen system error. If you've been running windows Xp, please do the following:
1. Insert Windows XP CD in the Pc.
2. Restart the PC and while in Bios, go to Boot Priority and select Boot from CD as your first priority.
3. Save and exit.
4. The PC restarts and follow the instructions on the screen. (Press any key to boot from the CD).
5.After system has finished, such will happen <Enter-To Continue R-Repair ESC-Cancel>.
6. Choose R to repair.
7. A black screen pops up, just read and type 1 and wait for the next step (password).
8. Put in your Admin Password or press "Enter".
9. Then type CHKDSK and press "Enter".
10. the system will repair the errors within the HDD and windows and later restart the PC. Good luck

If you attempt to install a piece of hardware or software on your PC computer that is incompatible with your system, you may see a blue screen with a C000021a fatal error warning. The easiest way to recover the Windows operating system from this type of error is to restore your computer to a previously working state.
1.Press the "F8" key on your keyboard when prompted during the boot process.

2.Use the up-and-down arrow keys to highlight the "Last Known Good Configuration" option. Then hit "Enter.
3.Use the up-and-down arrow keys to highlight the operating system version that you wish to boot up to, and then hit "Enter" again. The system will now restart to the last working version of your operating system, which will eliminate the C000021a fatal error.
Hope this helps

start in safe mode with command propmpt and type chkdsk /r/f and let the system get scan.

hello there
here is some information that should be able to explain this error and how to fix it ok?
best regards michael

1. How to troubleshoot a "STOP 0xC000021A" error ... presents advanced troubleshooting steps for the STOP 0xC000021A error. ... STOP: c000021a {Fatal ... Note Most STOP 0xC000021A errors occur because Winlogon. ...support.microsoft.com/kb/156669
2. "STOP: c000021a (Fatal System Error)" Error! RE: "STOP: c000021a (Fatal System Error)" Error! Ya, thats what I thought I might have to do ... RE: "STOP: c000021a (Fatal System Error)" Error! just input the ...www.msghelp.net/showthread.php?tid=66202 - 52k - Cached
3. How I fixed my Windows XP Stop c000021a {Fatal System Error} with ... How I fixed my Windows XP Stop c000021a {Fatal System Error} with Knoppix Linux. 2008 March 14 ... Message: Stop c000021a {Fatal System Error} The Session ...healyourchurchwebsite.com/2008/03/14/how-i-fixed-my-stop-c000021a-f... - 53k - Cached

damaged OS windows or most commom hard drive failer..

usually blue screen comes from unstable video memory or windows system or HD.
you may try
1) reinstall windows
2) change another HD to install windows
3) change new ram memory or change memories slot between one and another
if not fixed, to be sure your video memory damage which is insualted on board(separated with RAM), only the hardware repair can be fixed.

plz give your motherboard make and model and the operating version