I play lots on a dual core, and some on my old single-cpu desktop, and it happens occasionally on both.
What usually works for me is to click the Find button. The game sometimes hangs on one of the player's ships that has moves remaining. Do something with the highlighted vessel (move it, set it to Guard, etc.), and the game should take over again from there.
This doesn't work for everyone, but give it a try next time your game freezes.