autorecover
I think I know the feature you're talking about: "autorecover". If it's enabled, Word will have the file periodically under another name. According to the help, if Word is interrupted (e.g. by a crash), Word will load the autosaved version next time you start Word. So sayeth the help, anyway. I distantly remember it working for me on a couple of occasions in the far past. Sounds like an all-or-nothing thing: You start Word, and if it can recover, it'll offer to; if Word is silent, you may be hosed, at least as far as autorecover.
Good luck!