Are you shutting down all non-essential programs before trying to start the game?
Did you try verifying local files?
Try try re-installing the DirectX, and DotNet and Microsoft Visual C++ Runtime Library from their respective subfolders in
..\steamapps\common\dragon commander\_CommonRedist\
Try emailing support@larian.com, with a description of the problem and maybe a link to this topic.
There should hopefully be another beta later today, so that may resolve the problem.
