Hi optimus,I had the exact same problem (well, except it was on a different turn) but it was shortly after I destroyed that base.
I was ready to give up (after starting twice from the beginning) when my friend mentioned that he had the same problem but was able to overcome it using the AutoSave feature. It would crash, but he would just call up the auto-saved game and continue on.
So ... I tried doing that. I turned on the auto-save and got up just past destroying the base with a high expectation of an impending crash when ... nothing happened. No crash ... no way of knowing if the auto-save trick would work. Go figure. No big deal, at least I was able to finally go on.
I haven't finished the scenario though I think it's the best one I've ever played. After restarting twice, I think I just need a break from Star Trek (in between crashes, I played that other Star Trek one, "Battle for the Alpha Quadrant", or whatever it's called. That's also a good one!)