Multiplayer LAN loses Sync without crashing...
My friends and I (3 of us) were playing a multiplayer game, and after about 1 hour, the game lost sync-- it still ran, I was still hosting, but each of our games had replaced the other Human players with AI.
I have no idea how it happened. This is, though, the weirdest stable bug I've ever experienced.
Oh, and, we also were playing us vs. AI, 3v3v3, on a custom map, if that helps.