I don't know if you're still struggling with this problem, zirkoni, but I ran into the exact same problem on my system. I'm not sure what causes it, but I have come up with a workaround for you.
When you first load the game, it shows the Silicon Knights cinematic with the rotating cube and the sword falling into it from above. If you hit a key to skip past that cinematic (as I do), it'll take you to the double-doors with engravings of all the different unit types in the game. Once there,
wait for all previous cinematic sounds to stop playing! This can take a few seconds, so be patient. Once you hear the sound of soft music start to take it's place, then it's safe to open the double doors to the main menu. Once you do, you'll see the standard START, LOAD, LINK, and QUIT options, and a fire brazier burning on the steps. Note the sound effect of the fire.
Waiting for the soft music is the key. If you fail to do so, when you click any of the 4 menu items (START, for example), you'll be taken to the next screen, but you'll
still hear the fire sound effect in the background. This is the signal to listen for, because that tells you that your game is going to freeze up when you try to move one of your army's units in-game.
If you continue hearing the fire sound effect, the only way to remedy the problem (that I've found) is to exit the game and re-enter, making sure not to open those first double doors until you hear the soft music. My son and I have tried this several times now, and it works for us every time.
Hope this helps!
