What causes multiplayer OOS errors in LoR?

[JohnMK]

I'd love to make this game work in multiplayer with my friend I turned off Choose Religions but we played with Revolutions checked -- I know you can use Revolutions in MP as long as everybody chooses the same options. Anyway, we never had any options come up for our cities because we were well in control of them, no rebellious cities at all. So why am I getting OOS errors? We played fine for the first 3000 years or so, and now we can't push onwards. I'm playing with one other person, by the way.

Any ideas? Anyone have any experience here?