This particular error will produce a blue screen and an error message akin to the following:

Blue Screen error message Stop: c000021a {Fatal System Error}

Stop: c000021a {Fatal System Error}
The Session Manager Initialization system process terminated unexpectedly with a status of 0xc000026c (0x00000000 0x00000000).
The system has been shut down.

Unfortunately, this indicates a major system error and is a pretty serious issue. But there are things that you can attempt in order to resolve it.

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. It may not be possible to run Total System Care immediately with this error, but you would be advised to run it as soon as it is practicably possible.


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 this does no good, 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.