First check if you have the latest version of GCI (1.22.102), AP (1.52b.014). If not install it via Stardock Central.
Second does a reinstall help? How much RAM do you have?
Do you run under Vista, i heard that in this case there are problems.
Mail stardock support, because I don't think that the devs check this forum on a regular basis. There is a debug.err file i think, you can mail that.
Or you can use smart exception (get it via SDC). Run it play the game, when it freezes se has a debug file.