This was on a Windows 2012 R2 with WebRoot

Your PC ran into a problem and needs to restart

We're just collecting some information, and then we'll restart for you

If you'd like to know more, you can search online for this error: 0xc000021a

ANy ideas? I was trying to restart the Oracle database XNE onboard at the time...

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I am seeing this too...

#-o

If you cannot boot up following this error then you can try a few things.

The issue can be related to either the winlogon.exe file or the csrss.exe file being of the wrong version, being in use or being corrupted.

It can also be a driver or other software error.

The first thing we should do is try and repair our disk and check for errors. Download bootable Windows Media from here:download bootable Windows media 

Now once you have downloaded the above software, make a bootable USB or DVD.

Now boot into your PC using the media when asked to 'choose an option' choose troubleshoot and then select advanced options

Select Command Prompt

Type BCDEdit and look for the OSDevice property, this will tell you the drive letter which contains your Windows folder - may be D:

In the command prompt box, type chkdsk D: /f /r where D: is the driver letter you just got above, and press Enter

Allow the disk check to complete.

Now run 'SFC /scannow /offbootdir=D:\ /offwindir=D:\windows' in the same box, remembering once more to substitute the appropriate drive letter and see what results you get. This process should restore all of the system files to their proper conditions.

Next, in that same box again, run dism /image:D:\Windows /cleanup-image /restorehealth making sure you use the correct drive letter discovered above once more.

Which will restore all of the file drivers etc. to their proper states. If the process completes try staring Windows normally.

The file versions should now be matched and the system should start but if not, try entering the boot media again and under troubleshoot>advanced options try running start-up repair

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