Success?

C:\Users\stibbett>taskkill /im myapp.exe /f
SUCCESS: The process “myapp.exe” with PID 8548 has been terminated.

C:\Users\stibbett>taskkill /im myapp.exe /f
SUCCESS: The process “myapp.exe” with PID 8548 has been terminated.

C:\Users\stibbett>taskkill /im myapp.exe /f
SUCCESS: The process “myapp.exe” with PID 8548 has been terminated.

C:\Users\stibbett>taskkill /im myapp.exe /f
SUCCESS: The process “myapp.exe” with PID 8548 has been terminated.

How can Windows not know whether or not it’s successfully killed a process?

This is on Vista, where kernel improvements were supposed to make killing processes more reliable.