Auto save doesnt autosave! or...?

Hi! I adjusted the autosave settings a few days ago to 5 min or after each 5 changes. Just to be safe. And, you know what? Yesterday evening there was a power-cut!! It happens about once every 100 years or so here in Sweden, but it did happen yesterday. The PC and Sonar was running. I was in the final stages of a mix. Power went, didnt come back in a while, computer and all lights dead, so I left the studio and went home, feeling safe. "At most a have only lost the last 5 moves in the project" I thought.
This morning I came back to the studio, electricity is back, I fired up the PC and Sonar. What do I see? Last autosave version was yesterday morning, before lunch. I have lost the whole afternoons work, recordings and adjustments!!! Guess if I am disappointed!
 
Anyone has a clue as to why this happened? I have searched the different harddrives for autosave copies of the project but nothing. Only the original file and an autosave copy in the folder I have specified. But only old versions. Several hours old, with many things missing from the last hours of recording and mixing.
 
THankful for any tips.
 
Solong,
Martin

Yes! And you know what? I happened again today. Not the power failure, just Sonar crashed on me . And I hadn't saved my work for an hour or so. So, yes, I lost everything again, that is the last hour's work. Now I restarted Sonar and enabled versioning to see if that helps.
 
But, shouldn't autosave work without versioning? I can clearly see that Sonar does stop and save now and then!! So I was sure it works?
Anyone else have a comment on this?
 
THanks, Martin

Thanks Karyn and FAst Biker Boy. Since I changed to versioning I haven't had a crash. I dread the day now....

Isn't there anyone who have any experience of the autosave function?

[Ctrl + S] is my frequent friend.