I just had a very annoying incident. I had two scenes open in IC2012(64)PU2. Scene A was linked into scene B. I've been working on the geometry of A for two days, sometimes in A, sometimes in B. I saved A (but not

every hour or so. Then things suddenly went haywire and IC started producing error messages galore. Since I had just saved A a few minutes earlier, I simply quit IC without saving A or B. Then I restarted IC an re-opened A - just to find that all my recent work was lost

Indeed, the timestamp on the files was more than 24h old! Was that my fault, i.e. is that behavior expected? Or di something in IC go wrong?
Beat