Solved Recurring unexpected shutdown and BSOD c000021a, Startup Repair

[set9676]

This is my first post, so I apologize in advance for omitting any important information or additional ignorance on my part. I'm far from a computer expert.

My Gateway NV53 had a meltdown in late July (unable to boot, would crash in safe mode, unable to restore, etc.) and I was forced to restore the laptop to factory settings, losing all my files in the process.

It was working fine for about a month until last week it unexpectedly shutdown. On rebooting I got the BSOD Stop: c000021a error. After about 4 tries I finally got the advanced boot menu to load the system/startup repair, which seemed to fix the problem after about 30min or so.

I thought everything was fixed, but I got the same problem yesterday afternoon: suddenly crashes (no BSOD, just shuts down), with the c000021a error on re-start until I run startup repair which fixes the problem.

Any ideas on why this keeps happening? I have read that c000021a is often caused by 3rd party software updates interfering with WinLogon, which compromises the security of the system, but the crashes aren't occurring after downloading anything or installing new software (intentionally, at least). The first crash happened while I was using Skype, the second time while watching a YouTube video.

When I reboot after the startup repair, my Norton Antivirus definitions are out of date and must be updated, and there are always Windows Updates to install upon shutdown. This past time I also had to re-install Chrome. Is this because Norton AV updates or Windows Update is causing the crash, and startup repair is then removing these updates to restore the system?

Windows is currently operating normally, but I'm trying to prevent this crash from continuing to repeat itself. I´m getting sick of using startup repair every week. I have also turned off automatic windows updates for the time being.

As a side note, I was planning to purchase some DVDs to make a factory default disc so that I could repair the system if startup repair suddenly stopped working, but how is this any different from simply using the recovery manager in the advanced boot menu to do a full factory recovery? I have also read about using DVDs to create a system image. How is this different, and which method should I be using to be able to recover my laptop if startup repair stops working for me?

Thanks for your suggestions,
Spencer

 

[beret21]

DUDE just post the problem .................
LONG STORIES r kindda anoying !

Just the full error that appears on that bsod