Windows 7 Forums
Welcome to Windows 7 Forums. Our forum is dedicated to helping you find support and solutions for any problems regarding your Windows 7 PC be it Dell, HP, Acer, Asus or a custom build. We also provide an extensive Windows 7 tutorial section that covers a wide range of tips and tricks.

Windows 7: BSOD after Firefox update, Error c000021a

12 May 2017   #1

Windows 7 Professional 64bit
BSOD after Firefox update, Error c000021a

The verification of a knownDLL failed. system process terminated with a status of 0xc0000020 (0x0102c750 0x0000000).

Tried system repair with and without Windows 7 DVD and last known good configuration. All results in the same BSOD. Computer will not start in any Safe Mode. Startup Repair says it cannot repair automatically.
Unfortunately I cannot load(or don't know how to) the DM Log Collector because I cannot get access to the problematic computer. I used ESET SysRescue and ran several scans without success. I can, however, see the files on my C: drive using the ESET desktop utility.

History: Started having issues with computer freeze up after updating Firefox to 53.0. After the computer ran for half of the day, simply opening a new tab would completely freeze the computer. This happened on 3 computers - 1 desktop, 2 laptops. After the latest freeze up on the desktop, a press of the reset button on the tower lead to the BSOD.

My System SpecsSystem Spec
12 May 2017   #2
Layback Bear

Windows 10 Pro. 64/ version 1709 Windows 7 Pro/64

Please complete this needed tutorial by Brink.

Blue Screen of Death (BSOD) Posting Instructions - Windows 7 Help Forums

My System SpecsSystem Spec
12 May 2017   #3

Windows 10 Pro

Hi snsjets,

2 main causes in this kind of situations are the hard drive(s) and RAM.

For 1 of the tests below, HDTune, please use the bootable Win10PE from Windows 10 Recovery Tools - Bootable Rescue Disk - Windows 10 Forums to run them. This Win10PE has software preinstalled.
You could also try and use Macrium Reflect, also preinstalled, to fix boot issues if the hard drive and RAM appear fine.

BSOD after Firefox update, Error c000021a Diagnostics Test BSOD after Firefox update, Error c000021a

Note   Note
Please run HDTune first, in the order posted!

Run HDTune to
  • check the health,
  • scan for errors, no quick scan but full scan
  • run a benchmark.
It may take some time, but please take the time you need to perform it properly.
When above is done please make screenshots of the following
  • the health,
  • the error scan,
  • the benchmark incl. following
    • transfer rate,
    • access time,
    • burst rate,
    • cpu usage.

Run SeaTools DOS to check the integrity of your HDD. SeaTools for DOS and Windows - How to Use - Windows 7 Help Forums
Run the long test.
Note   Note
Do not run SeaTools on an SSD as the results will be invalid.

Make a photo of the result and post it.

Run chkdsk
Disk Check - Windows 7 Help Forums
Use option TWO with parameter /r
Upload the chkdsk log Check Disk (chkdsk) - Read Event Viewer Log - Windows 7 Help Forums

BSOD after Firefox update, Error c000021a Diagnostic Test BSOD after Firefox update, Error c000021a

Run MemTest86+ to analyse your RAM. MemTest86+ - Test RAM - Windows 7 Forums

Note   Note

MemTest86+ needs to be run for at least 8 complete passes for conclusive results. Set it running before you go to bed and leave it overnight. We're looking for zero errors here. Even a single error will indicate RAM failure.

Make a photo of the result and post it.

If errors show up you can stop the test, remove all sticks but 1 and test this single stick in each slot for 8 passes or until errors show, switch sticks and repeat.
If errors show up and you see them a lot later, no problem, the errors don't affect the test.
My System SpecsSystem Spec

16 May 2017   #4

Windows 7 Professional 64bit

Hi Axe0,
Thank you for the reply.

I installed and ran Macrium's Fix Boot Problems utility - no change.
I did not run SeaTools since I boot from a SSD.
I also ran Malwarebytes that came with the Win10PE desktop - 0 threats.

I ran HD tune:
Attachment 398760

Attachment 398761

Attachment 398762

Attachment 398763

I ran chkdsk:
Attachment 398764

I tried to install and run DM log collector from the Win10PE desktop but this is what happens:
Attachment 398765

Attachment 398766

Memtest86 is 14 hours in (still going) and no errors yet:
Attachment 398767
My System SpecsSystem Spec
16 May 2017   #5

Windows 10 Pro

Those errors with the DM Log Collector are understandable.
Besides of the errors, does the DM Log Collector finish and leave some logs?

Please do note, it is recommended to run the hard drive tests on all partitions/drives. It occurs often that not the boot drive, but a different drive is causing issues.
My System SpecsSystem Spec
16 May 2017   #6

Windows 7 Professional 64bit

I guess I didn't look for DM logs under the error windows. I will look for them next time I'm on the Win10PE desktop.

OK, I will run HD tests on the other partitions and the HDD.
My System SpecsSystem Spec
17 May 2017   #7

Windows 7 Professional 64bit

Hi Axe0,

I ran 8 passes on Memtest86:
Attachment 398806

I ran SeaTools on my HDD:
Attachment 398807

I ran chkdsk on my HDD:
Attachment 398808
Attachment 398809

I ran HDTune on my HDD:
Attachment 398810
Attachment 398811
Attachment 398812
Attachment 398820

I ran DM log collector on the Win10PE desktop (still with errors) and these are the files:
Attachment 398821
My System SpecsSystem Spec
18 May 2017   #8

Windows 10 Pro

Run the long test for Seatools.

The rest looks good, unfortunately the uploaded logs aren't of much use since most of it is corrupted (size is 0).

Could you provide your PSU and cooler.

Has SFC been performed on the system?
My System SpecsSystem Spec
18 May 2017   #9

Windows 7 Professional 64bit

Ran SeaTools long test
Attachment 398858

PSU is Antec BP550 Plus

Cooling is provided by 3 fans - front, back, and top of case

I attempted sfc (multiple times) after booting from the Windows 7 disk and this is what comes up: There is a system repair pending which requires reboot to complete. Restart Windows and run sfc again.

I attempted sfc from Win10PE desktop and this: Windows Resource Protection could not perform the requested operation.
My System SpecsSystem Spec
19 May 2017   #10

Windows 10 Pro

I presume stock cooling.

Do you have any peripheral attached?
My System SpecsSystem Spec

 BSOD after Firefox update, Error c000021a

Thread Tools

Similar help and support threads
Thread Forum
BSOD unknown reason, error c000021a. Please help
Hello guys, my computer will not startup. It crashes at the Windows startup screen with a BSOD that states: STOP: c000021a verification of a KnownDLL failed. Sorry I don't know how to get you guys my system or dump files without being able to login windows to run the programs. Things I've...
BSOD Help and Support
BSOD c000021a Fatal Error. Pls Help
Hello Guys. I have this problem a few days. I tried a lot of thinks what I found on internet but nothing works, I m really tired. Please help me. I need my computer back, because I have a lot programs in there. I think that this problem started when I connect second monitor in HDMI. Is it...
BSOD Help and Support
BSOD playing ragnarok then restart, error c000021a
I was playing ragnarok online then suddenly i lag so much my CPU runs on 100% i cant click i cant move nothing then i finally move my cursor so i restarted i got BSOD c000021a i got this month ago but i read online says that just reformat it then your good i dont know if that was real to fix the...
BSOD Help and Support
BSOD on startup c000021a {fatal system error}
Hey fellas, i restarted my compure about an hour ago for it to complete a windows update, on the logout screen and showed: installing updates, it jumped from 10% to 20 and thirty and the skipped to shutting down. when starting back up again i got a BSOD saying: STOP: c000021a {fatal system...
BSOD Help and Support
BSOD, Stop: c000021a fatal system error
Dear Support, I have a Sony Vaio VPCZ1 laptop which has been working great up until yesterday. I now have the following problems: - When choosing to boot normally I get BSOD; STOP: c000021a {Fatal System Error} The Windows Logon Process system process terminated unexpectedly with a...
BSOD Help and Support

Our Sites

Site Links

About Us

Find Us

Windows 7 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 7" and related materials are trademarks of Microsoft Corp.

Designer Media Ltd

All times are GMT -5. The time now is 16:44.
Twitter Facebook Google+