Does this happen with any project? This could be caused by a mistake in your code or in one of the addons you are using. Just a few days ago I found a bug in a popular Spline plugin by rexrainbow, where it can go into an infinite loop and freeze.
I have one rex plug the rotate since I have an Osprey and it's easy to get that counter rotation for the two rotors. I will unpin them and give it a shot. However it was also doing this crash before I even placed that object and was only using player and enemy tanks, one each in some case and then as many as four or five but that crash was still happening randomly and even now it is still random, did it once this morning already and I had to reboot the machine. At this point I don't really have a game per se but only trying to get my mechanics and placements for the objects for a first map of a simple little tank game. I believe it is something related to using this win 7 64. It isn't a real high resource computer but a simple Xeon 3Ghz 4 core with 8gigs of Ram. I need to run some simple tutorials from construct and see if it does the same with little or no content.