Blue Screen

I'm just a helpful Unchecky user. Here's what I found out:

STOP code C000021A is STATUS_SYSTEM_PROCESS_TERMINATED, which means that a vital Windows system process crashed or stopped operating safely.

The message text and the following code (0x0000005) ought to tell us exactly why the system process stopped running, but in this case it's a very vague message ("Fatal Error") and the error code you gave seems to be missing a digit (there should be 8 digits after the "0x"). If I assume this was an error in reading the number off the screen and that it was supposed to be 0xC0000005, then it is an "Access Violation", also known as a "segfault" - unfortunately quite a common error in computing and one that could occur for any number of reasons.

The final two codes are listed by Microsoft as "Reserved" for this particular STOP code, so they likely contain no useful information.

Microsoft does note that the installation of a new system service can cause this error if something goes wrong in that service (note that Unchecky installs a Local System service in order to monitor your installers).

In short: it's very likely that Unchecky is causing the BSoD, but there is very little to say why.

It looks like there is something that messes directly with Unchecky service and the way it operates against the kernel-mode subsystem (in this case: winlogon.exe+ad15).
What antivirus software do you use?
Have you ever check the system against rootkits or other malware? There is a possibility for it to intercept Unchecky service calls and mess with them, so you might get this error. I suggest running a GMER scan.

Hi John,
Unchecky doesn't use a driver, so it shouldn't be able to cause a BSoD by himself.
I see two possible causes here:

• Your OS/hardware has an issue, and the installation of Unchecky triggered it. For example, you might have a broken hard disk, and Unchecky might have been installed on the faulty part of it.
• You have an incompatibility with a low-level software, such as an antivirus program.

Did you try installing Unchecky again on that PC? Do you see the BSoD every time?

Hi RaMMicHaeL,

I am not John but I'd like to comment regarding your statement that "Unchecky doesn't use a driver, so it shouldn't be able to cause a BSoD by himself."

For this particular BSoD, Microsoft notes that "this is one of the few situations where the failure of a user-mode service can shut down the system." Unchecky DOES run a user-mode service.

I agree with Lukasz032 here, that it could be something like antivirus interfering with Unchecky's system calls.