So, just another repeat of testing...
DLL #2, 400 rounds in, mostly standard settings on huge Erebus, no OOS.
I did find an unrelated crash though. Not sure how repeatable it is, since when I tried to go into the world-builder to repeat it, the world crashed before that could happen (heh).
I had the Nox Nexus (or whatever the Esus holy building is) and was being invaded by Basium. His stack of units walked over my invisible, undeclared nationality unit (not a nightwatch, a shadow or assassin--whichever's the next step up. I was the Khazad, so all dwarven equivalents were applicable). All was well, except I wanted to upgrade my unit (he hadn't moved yet) so that when the stack moved OFF of his tile, he could follow them with an assassiny attack.
Except, as soon as I upgraded his unit type, everyone's game crashed and we had to revert to the last autosave.
When I tried to repeat the experiment in the world editor this morning, I gave myself one city with the Nox Nexus, all technologies, and put myself at war with the infernals. Put some imps in my territory, set up a field of nightwatches (who, since they were in the Nox territory, were invisible as well as undeclared nationality).
As soon as I end-turned, it crashed in the same way. No upgrade required.
Perhaps it's a problem with stacking invisible undeclared-nationality units with invading forces? For all I know, before I upgraded that unit, I had previously declared his nationality but the upgrade reverted him to undeclared... this would match with the Imp scenario, where the imps probably tried to move onto an undeclared-invisible nightwatch square.
Sorry I'm not terribly more helpful with that particular multiplayer-encompassing CTD, but I just spent all last night studying for finals sans sleep... soo... gnight? =P