Are you shutting down all non-essential programs (especially anti-virus) before starting the game?
Did you try running the game directly from ...\steamapps\common\dragon commander\shipping\DCApp.exe
or right clicking it and running as administrator / right clicking, selecting Properties and switching to the compatibility tab to try different options?
Is your desktop resolution particularly high or at a non-standard refresh rate, or something, that the game could not be handling properly when it tries to initialize?
