Finished my first day messing around with Alpha. Was able to successfully find a consistent crash to desktop error. The error itself doesn't give any details. and simply kills the game and returns to desktop. Fairly easy to recreate though.
The crash seems to simply be an overcrowding error. I found it first while playing with the full load of current opponents. (3, plus me). My game was a strictly peaceful research one, in which I attacked nobody and simply worked through the research tree. On turn 228 the other 3 species had pretty much taken over the map, and then after ending my turn on 228 the game crashed.
At first I messed with several graphics functions and reloaded an autosave, however the crash continued. I tried resetting my computer to no avail. I then tried reloading to an earlier game. Doing this made the crash occur 2 turns later on 330.
After proceeding through an elimination round, I discovered that the crash occurred when there were simply no more room for expansion. All of the colonized planets had been occupied. The mass colonization occurred with A.I. leading the way, as I simply researched throughout the game, and let the computer expand.
I tested my theory by recreating a new game with just myself and another A.I. species. Because there was only 1 opponent the crash didn't occur until turn 301. However, just as expected, when there were no more worlds available to colonize the game crashed. It seems to be an A.I. error where the A.I. doesn't know what to do after colonizing everything, and because they weren't technically at war with me.