This article is intended for advanced computer users. If you are not comfortable with advanced troubleshooting, you might want to ask someone for help or contact Technical Support.

When you use a server or a workstation that is running one of the operating systems that is listed in the “Applies to” section, you may receive the following error message:
STOP: c000021a {Fatal System Error}
The Windows Logon Process system process terminated unexpectedly with a status of 0xc0000034 (0x00000000 0x0000000)
The system has been shutdown.

Download Recommendation

The first thing to try with regard to this error is to attempt to clean the registry of your computer. A good way to do this is to download the Total System Care, which will do an excellent job of cleaning your registry and often sort out the problem in itself.


More Information and Manual Resolution

Firstly, it is important to note that there could be any number of causes for this issue, an almost infinitesimal number which cannot possibly be covered in one article. What can be dealt with fairly succinctly are approaches you can take to attempt to resolve it.

The first and most obvious thing to do is to attempt to boot the computer in safe mode, and then do a full system restore to a point when your computer was working. You can then re-install any devices or programmes that have been removed by this virtual step back in time. To activate Safe Mode, hold F8 when your computer is initially booting up. Once you’ve reached the desktop in Safe Mode, type ‘System’ into the Start search box and press Enter once ‘System Restore’ is highlighted. You should then be able to run the system restore utility.

If you’re still having problems then start your computer by using the Last Known Good Configuration. To do this follow these steps:

When you see the ‘Please select the operating system to start’ message, press the F8 key.

When the ‘Windows Advanced Option’s menu appears, select ‘Last Known Good Configuration’ and then press the ‘Enter’ key.

Attempting to further troubleshoot this issue is extremely complex due to the vast number of possible issues that could have led to the issue, but if you seek out the Microsoft website there is an article which gives an inordinate amount of information regarding possible troubleshooting that you can engage in.

If this does no good, and / or it is impossible to start the computer in Safe Mode then you will almost certainly have to completely reinstall Windows. However, you would be highly recommended to contact Microsoft first as they can advise you on whether there is any way for you to salvage the data saved on your hard drive. Reinstalling Windows will wipe this, and if you can’t start your computer then there is no obvious way to copy your data to a USB drive.

In order to reinstall Windows, you will need the disc which was provided when you bought your computer.

If reinstalling Windows does no good, you must have a serious hardware issue, and you should either seek manufacturer’s advice or take your machine to a computer store in order to be serviced.