STOP: c000021a {Fatal System Error} blue screen on boot, but loads fine with "Disable Driver Signature Enforcement" RRS feed

  • Question

  • This particular machine(Vista Home Premium x64) had two things done to it two days ago.  #1 a cheapo usb-to-serial adapter was added(Prolific 2303 drivers) and #2 ATI Catylst drivers upgraded to 9.6.

    Ever since that day, when the computer is started, it tries to boot, then restarts, then goes into repair mode, can't automatically repair, asks to restore back to a restore point, do that, boots once fine then the next time you restart, it'll do the automatic restart and need to repair.

    When I disable automatic restart on error, I see a STOP: c000021a {Fatal System Error} bluescreen.  This unfortunately doesn't tell me where the error really is.

    When I select safe mode, it restarts.

    When I select "Disable driver signature enforcement", it boots fine.  Everything seems to function normally.  I reinstall ATI's 9.5 set and I remove the usb-to-serial adapter and uninstall the drivers.

    Still can't boot unless I select "disable driver signature enforcement".

    When I select "Enable boot logging", no ntbtlog.txt file is created(or it gets overwritten when I boot using "disable driver signature enforcement" or something).  I don't see anything in event viewer indicating which file windows is stopping on.

    I've run two virus scanners and a spyware scanner.  I've run a chkdsk.  I've run sfc /scannow and it didn't seem to find any problems. I'm already back to my oldest restore point, I've uninstalled the only two things that where new since this machine was working perfectly.

    I ran sigverif and its indicating 71 unsigned files, most of them from Microsoft, so I'm unsure what to do about that.

    I'm being driven insane.  There's obviously something that's triggering windows to not be able to boot unless I disable the driver signature enforcement.  Where do I find the cause?  I can do without the latest ATI driver, I can do without this usb to serial driver, but I can't deal with having to hit F8 everytime I need to restart.

    • Edited by Don Tan Friday, June 26, 2009 1:53 AM Fixing Thread title bug
    • Edited by Jason.Smith Friday, June 26, 2009 6:29 PM fixing double encoded title
    Thursday, June 18, 2009 12:49 AM


  • Hi,


    Thanks for posting in Microsoft TechNet Forum.


    First of all, I would like to share an article on error c000021a with you.


    c000021a Error



    Meanwhile, please understand that to troubleshoot this kind of kernel crash issue related to blue screen, we need to debug the crashed system dump and analyze the related source code if needed. Unfortunately, debugging is beyond what we can do in the forum. I'd like to recommend that you contact Microsoft Customer Support Service (CSS) for assistance so that this problem can be resolved efficiently. To obtain the phone numbers for specific technology request please take a look at the web site listed below:




    If you are outside the US please see http://support.microsoft.com for regional support phone numbers.


    Hope this helps. Thanks.
    Thursday, June 18, 2009 3:59 AM