Shut down operating system by killing task

Question

I came across quite an odd error recently and was wondering if anyone has any insight into it. I can't find any reference to such a scenario on Google so here goes...

The rough sequence of events is like this:

1. RDP into a Windows 2008 R2 and start working in SQL Management Studio
2. Try to log out without closing SSMS first
3. Screen goes dark and gives me the "Background tasks are waiting to close" information
4. I assumed that SSMS would be asking me if I wanted to save my SQL script, but I was unable to switch back to the task
5. Taskbar was still usable so I right clicked and opened Task Manager, went to the process list and tried to end ssms.exe
6. It warned me that by ending this task the operating system would shut down and I might lose data. The button to do the deed was greyed out until I ticked a box to accept that there might be data loss.
7. So I ticked the box and pressed the accept button. True to its word, shortly afterwards I lost my RDP connection and had to wait for someone at the remote end to restart the VM.
8. When the OS came back online it reported that a blue screen error had occurred.

Unfortunately during this I didn't think to get a screenshot so I'm going from memory. But I was surprised - I kind of thought these days with process isolation and what-have-you, one user process couldn't bomb out the whole OS - more likely a low level system process like a driver. And I've definitely never seen any functionality like that in Task Manager before.

So... has anyone come across this before? And is there say, some Microsoft documentation that will explain what I came across?

EDIT - to clarify the symptoms, once the SMSS process is killed it causes a blue screen, then the system restarts itself (no manual intervention was required). And here is the message text from Task Manager in case anyone in future is googling for this: "Ending this process will shut down the operating system immediately. You will lose all unsaved data. Are you sure you want to continue?" And the check box states "Abandon unsaved data and shut down."

Answer 1

smss.exe is an essential system process in Windows (it is the Windows session manager), and it is not related in any way to SQL studio. If you kill it (and same goes for other system processes, like winlogon.exe or the event logging service), the system might trigger a reboot (last time I've seen that on XP, it was with the countdown window generated by the InitiateSystemShutdown API, as visible in the webpage mentioned below, but I've also seen it rebooting instantly with a blue screen).

Actually, killing smss.exe along doesn't seem to trigger a blue screen or reboot (at least on the WinXP virtual machine where I tried), however, killing it might produce heavy side-effects. On Windows 7, if you try to kill the smss.exe process with the task manager, a system shutdown is automatically initiated, as stated in the dialog box that the task manager displays.

Some details about killing SMSS and other system processes here: http://blogs.technet.com/b/markrussinovich/archive/2005/07/24/running-windows-with-no-services.aspx