I'm just assuming that a memory leak is what's going on, but I wanted to report that windows actually popped up and warned me that it was low on memory and that I should close Fallen Enchantress. I've never seen that happen before for any program. I'd been running a game for about 5 hours straight at that point. Just prior to closing FE interface elements began to disappear which is what alerted me that something was wrong. For example the quick navigation stuff in the upper left vanished, on the research screen labels were missing for some techs, tooltips stopped popping up, etc. Hope this report is of some use,