Games closes while alt-tabbed?

[agc]

Cross-posting this from the Bug Report forum in case someone here might have an answer:

 

I've had the game close itself numerous times today while I've been alt-tabbed, most recently just a few minutes ago. It's highly frustrating to be sitting in queue for over 20 minutes, alt-tab to look at something, and then when I go back to check the queue the program is no longer running. No errors or anything,

 

What's going on?