I'm having the same problem with windows 7 x64. The game appears to be hitting the 2gb virtual addressable application space limit and crashing. Sins of a Solar Empire had this problem, so did Supreme Commander and a few other games.
I'm guessing they just haven't optimized much yet and textures are eating way to much.
For the purposes of beta testing it would be nice if we can get the .exe to be Large Address Enabled?
It won't solve the problem, and will only work for 64bit OS(or 32bit with a tweak to some extent), but it may be enough to postpone the problem long enough to play through.
I used Visual Studio 10 to add large address aware, after I test it more I will give a detailed bug report.