Hi there!
I encountered the same problem. The crashes begin in one specific time, all the saves after it just keeps crashing. I am posting a link to one such save. It is also from steam version. (just press the "stáhnout" button, sorry it is in czech) http://uloz.to/xYJfaDqP/2013-06-07-17-31-44-rar
Edit: Homewer the game as such is awesome, best X-com remake I know (nothink against Firaxis )!