I actually had my first OOS (on turn 1) with patch H today. Since I had been saying I hadn't had any, and then all of a sudden there one was, I decided to test a little bit. We started and restarted and restarted maybe 30 times or so to see if we could figure out the cause.
One thing I noticed happened each time we went OOS, was that one of us had gotten a popup of some sort. Each of the times I got a popup and we went OOS it was on the same turn that I got one of the new "flavor" popups. By this I mean when you meet the Lanun and Hannah steals your hat for example. Once we even went OOS when she got one of the normal popups you receive when meeting leaders. These would be the ones where you can continue into the trade screen.
We didn't get these "flavor" popups every game, but it seemed like each time we did, we went OOS.
I can safely say it's not a Vista issue, or at least it's also affecting XP machines. For the record, I don't recall any OOS problems in my games for several patches. Patches F and G worked fine for us. This would be the first in quite a long time.