This strikes me as nit-picking and not a meaningful distinction. If something was going wrong on a win3.1 machine to the point that it no longer worked properly

This strikes me as nit-picking and not a meaningful distinction. If something was going wrong on a win3.1 machine to the point that it no longer worked properly, you'd hit ctrl-alt-del and get a blue screen. It's not like you hitting ctrl-alt-del made the computer unstable, you were just poking the cooperative multitasking system (by generating a magic, meaningful system interrupt) into realizing it was already unstable. If you got to the point of seeing that blue screen it was really really unlikely you'd never recover system stability without a restart, thus it was still a blue screen of death. Of course, you were free to try if you wanted to. But most likely whatever crashed or froze up that process spewed a bunch of crap all over areas of memory it had no knowledge of and fucked a bunch of other things up. The win32s didn't need that because they were pre-emptively multitasked almost all the way down and could detect their own failures better.