We both updated to 1.12, tried again, and it lost sync again with the same style (this time, cutsom map, five teams of 2.) We saved and loaded, and it somehow preserved the sync loss, like we're both playing separate games and it saved them both. We had the second person's comp save and host it, same issue.
Bummer, eh? Takes about 1 hour to lose sync, sucks like crazy. We're looking into whether or no it could be our wireless network, sinc it appears this issue is only prevalent when it's my computer involved, but it seems my comp causes this issue. I'm using a vanilla SP 2 xp dual boot on mac, if that helps. He's using dual boot xp on mac, as well, but it seems he doesn't have this issue with other people.