Problem With Campaign Mode in HTW

I have have followed the installation procedure completely and everything besides the single player campaign mode works correctly. I noticed though, when I tried to play some of the factions in some of the eras such as the Greeks and the Persians in the Persian Wars Eras and the Macedonians in the Classical Era the Strategy map would not load up. What would happen is the screen with the red loading bar would "load up" completely and then crash and go to the desktop screen. How might I go about fixing this problem?

Have you set your unit size on default?

Cheers,

LZoF