Help Needed to Fix 0xc000021a eror with windows10

[Peter Elliott]

Hi.im running a Dell Optic lex 755.Quad Core.4 Ram.1 T.PC.Just recently install the free version of windows 10,then a problem happen out of the blue.nothing was change,installed or uni stalled at the time.I started my PC,instead of loading, a blue screen appeared with an eror (0xc000021a).I Googled the eror which eventually brought me to this site.there was a fix which I tried,but it didn't work,it stated to run a S.F.C. Scan,system File Checker Scan to look for corrupted file.It stated to go to command prompt and type in sfc/scan which I did and it came back,"could not complete request".So then I tryed to reset windows 10 which it also stated.After it was reset it loaded.but then the pc started to update drivers,then it reverted back to the blue screen with the 0xc000021a eror.I know its somthing to do with one of microsofts up date,maybe a corrupt driver or somsort.Tryed resetting again,whith the thought in mind that when it was reset I would disable in settings " update" then find a program on the Web that could scan and fix the PC,but when the PC reset itself,the first page "wallpaper" came up were the next page is were you put in your password to get to the desktop,well it has stuck on the wallpaper page,nothing works,no mouse or key board,I tried resetting and and again but still with the same out come.landing on the wallpaper page before you enter your password.Does anyone have an answer to this problem.Please Could You Help me.Thankyou very much in advanced for your help if you decide to help with this challenging problem.The only other thing I can think of to do is to re-enstall windows 7 if I can't fix this problem,but I did,do like the feel of windows 10 and would love to keep it.I just don't know .Please help.Thankyou for your time.
Peter Elliott

 

[Trouble]

.Just recently install the free version of windows 10

Have you considered going back to the previous version of Windows?
That is generally an option for 30 days or so after upgrading. Might be your best bet.
Otherwise you could boot from the installation media
The installation media can be obtained through either of these two resources.

https://www.microsoft.com/en-us/software-download/techbench
OR
http://www.microsoft.com/en-us/software-download/windows10

Once you have the ISO, you can use ImgBurn to burn it to a DVD or Rufus to burn it to a USB ThumbDrive, either of which you can use to boot your computer.

When you've managed to boot from the installation media you need to click the Repair Your PC link on the second page after the Choose a Language and Keyboard layout page.
That should get you to the Advanced Troubleshooting options. Use the Command prompt option and type
bcdedit /set {default} bootmenupolicy legacy
hit enter
reboot and keep tapping the F8 key it should produce a boot option screen allowing you to select safe mode. If it's a driver issue then, a safe mode boot with minimal drivers might help.

 

[Peter Elliott]

Thankyou very much for your advice yon have been reallyhelpfull.Thankyou.I think your right,going back to my old windows 7 is the best bet.unfortuatly I'm past the 1 month of instalation of windows 10, so it looks like I'm going to have to reinstall Windows 7,will my pc still be registered with the same windows 7 installation.I mean,I am using the same windows 7 instalation disk as I installed on my pc as before.will it accept it as the same pc when it comes to registering it.as I understand it your only allowed to install the windows 7 instalation cd a number of time's,I think it 4 times or it maybe more,will I of lost 1 instalation of windows 7 on the windows 7 instalation cd or will it be remembered when coming to registering windows 7 again.Thanks again for the info,I'v never used theses sites before,but I have found them really useful and will be using them a lot more,if only just to learn about things. Regards. Peter Elliott

 

[Trouble]

I pretty sure, you'll be fine.
As long as you are installing the same version and using the same product key.
The worst that might happen is you may be required to use the automated phone activation system to activate the product again.