I have a save game of when I hit the end turn button it locks up in the sense the button does not stop being greyed no matter how long you wait. However you can click on objects like planets and get stats and such so it is only partly 'locked up' I suppose. I need to kill it in task manager which does not report it as non-responsive which I suppose it technically correct. If anyone from SD would like me to send you the save game file let me know where to send it to.
