Call it a hunch, but I think it has something to do with fighters. I rushed early in the game for Executor, so I could go AFK without losing my home planet; I did this just to see how long the game could run without a crash. About 30 minutes later I returned. Just then an MC80 came into my gravity well and launched fighters. The game crashed. Thankfully I saved minutes before this ship entered my gravity well. I reloaded the last save and instead of waiting around for the MC80 to once again enter my gravity well, I sent executor into the next gravity well (Where the MC80 came from) There were several MC80s, but none of them had their fighters launched. There was no crash during this skirmish. If it isn't a strike craft issue, then it must be a another problem occurring with the other races.