Beta 5 Now Continually Crashes and is Unplayable

For the past three days, I've been playing Beta 5. I can typically play for 40 minutes to an hour before the game hangs or crashes.

Now, I am finding that after having changed my game graphics settings, and then setting them back to lower quality, that GalCivIII immediately crashes.

The crashes occur immediately after a new or saved game loads.

Sometimes, I still hear the music playing, but nothing happens when I move the game cursor around and click on the UI elements or game map.

Other times, the game just disappears, and I see my desktop. I then see that my Steam game load screen shows its connection needs to re-sync.

In any event, I can't play the game any more. 

Are these bugs in the game or issues related to play via Steam?