Hi there,
yesterday I was practising a bit. Turned on the “timelapse” function (very cool. Would be a blast if one could define one fixed view for every screenshot)
As always when one is new to a software I pressed maybe one or two wrong buttons during final rendering.
Zbrush freezed.
Timlapse and final sculpt gone.
I read about “Recovered Files”
Aaaaaaah. 
Looked in there - Recovered tool from 12th, recovered_Document.ZBR from 19th which I couldn’t open.
Oooooooh.
Searched for some possibilities to increase saving rate. (Crashes one or two times a day - maybe beginner operator fault) Just found a button.
Checked online documentation and found this inbetween release notes for zBrush 3.5:
http://www.pixologic.com/docs/index.php/Tips_and_Tricks#Auto_Recovery_Incompatible_with_Windows_7
Is this still actual state? Auto Recovery was switched on by default installation.
My system:
Win 7 64 Bit Ultimate
3,2 Ghz Xeon
12 Gig Ram
Quadro 4000
Thanks in advance.