Ah, ok, sorry I was just trying to be helpful, I wasn't trying to teach you to suck eggs :)

But my main point was (that I implied, but I didn't say) is yes, I remember killing off early versions of microsoft security essentials (when that was its name) with task manager too. Logically, back then the process didn't have a restricted ACL, but it now does.

I didn't actually know you could specify the system user when killing a process with taskkill, thanks