I alt+tab all the time, but it never crashes. Well, due to alt+tabbing. I use two monitors, so I always have this forum right next to me when I play. Handy, in case there's something I want to know.
The game freezes sometimes, though, and when it does, alt+tabbing usually makes the error come up, so I can restart it.
It's not really an issue anyways, as the game autosave even if you think about doing something.