What happened to my changes in this damn Excel file?

About 30 minutes ago, I was raging to find out that for some reason, MS Excel 2010 had not saved all the changes I had made and saved yesterday. I can vaguely remember that the program once crashed and 'auto-recovered' my last changes. After that I saved those results to another file, which I also overwrote.

Soo.. now today when I opened that overwritten file, all my changes were gone, boo. The built-in recovery features (unsaved files) of MS Office did not help at all - basically no back-ups were to be found anywhere.

However, I was able to recover the file through the Win7 feature 'previous Versions' .. that is, right-click on the file in the Explorer > Properties > Previous Versions. There you find a list of backups made by Win7 every time you change/overwrite the file. :D

I'm not entirely sure whether it was exactly this feature which caused the problems or whether this was caused by Excel itself. Anyway: annoyance.