Did you try a just a skirmish, rather than the multiplayer campaign (select at the top right of the lobby, above the map)?
You can switch to LAN rather than Online, and not need to bother locking any slots if you just want to play against the AI. At least in previous betas locking slots could cause the game to crash.
ORIGINAL PROBLEM: Game would always crash loading RTS maps in campaign mode or loading the skirmish map.
PROBLEM EXPLAINED: Locking the slots in the lobby will cause the game to crash while loading the skirmish or RTS portion of the campaign. This happened 4 out of 4 times (3 during the campain while loading the RTS and 1 when loading a skirmish map. I had ZERO successes loading the RTS maps with the lobby slots locked.)
SOLUTION: Do not lock the player slots in the game lobby and the game should no longer crash while loading the RTS/skirmish maps.
Thanks Raze. Problem solved.
