I hate computers eating documents - happened to me several times when I was writing up my PhD thesis. Resurrecting what I'd just written then was fun. That's when I learnt to save as I go along - and to be honest I have the autosave function in Word turned on for a reason :D Lost too many important documents for work not to. Last week I lsot the best part of a lecture thanks to PowerPoint crashing on me - thankfully I had backed it up so it was in fact only 20 mins or so's work I lost but still....

Have to agree it is frustrating - but your best friend is Ctrl-S - use it regularly and this things will hopefully be a thing of the past :D