There are various possibilities as to the cause of your BSOD and subsequent error message, see below provided courtesy of Microsoft;
The STOP 0xC000021A error occurs when either Winlogon.exe or Csrss.exe fails. When the Windows NT kernel detects that either of these processes has stopped, it stops the system and raises the STOP 0xC000021A error. This error may have several causes. Among them are the following:
- Mismatched system files have been installed.
- A Service Pack installation has failed.
- A backup program that is used to restore a hard disk did not correctly restore files that may have been in use.
- An incompatible third-party program has been installed.
I suggest that we first of all check to see if a driver is causing the issue by running Driver Verifier;
1. Click Start
2. Click Run…
3. Type CMD and press Enter
4. In the new box, type verifier and press Enter
The Driver Verifier Manager utility will open up.
Select the Create standard list option.
In the next screen you can choose to auto select a driver or select from a list, please choose the auto select option and then restart the computer and see if this causes the system to crash, if it does it should identify the driver responsible.
Please note that DV may need to be run for many hours before a crash may occur so you may need to be patient, it will not compromise your computer in any way. To disable driver verifier when done go to start, run and type in verifier /reset Click on OK and you're done.
Going offline now as I have an early start in the morning but will try and check back before heading off to work.