Thanks for the log files. That is super odd that it is sometimes happening and sometimes not, and that the default settings seem okay. :/
There is one other guy also with this problem intermittently, if you want to compare any notes:
http://www.arcengames.com/mantisbt/view.php?id=15650A new version 7.060 is now out, hopefully that helps. There were some errors in your logs that made it seem very likely that automatic update checks were getting killed by some form of antivirus. Some people have said Avast continues to still run and randomly kill games even when disabled, from what I've heard. Not just our games; it's been kind of nutty.
Anyway, I should have mentioned this before, but in your settings.dat file inside your RuntimeData folder, you can add/change the following line:
AutomaticallyCheckForUpdates:1
to
AutomaticallyCheckForUpdates:0
That would prevent the crash if it is indeed update-check-related. One way or another, even if Avast is still killing the game, that would stop it for sure, because Avast would only be killing it because of the call out to amazon to see if there are new updates or not. With that off, Avast would be fine with the game.
You can restart steam to force a new update.
No problem on the minecraft reference, I also love it.