During ground combat against a scout, on the farm map, the game refused to start my next turn. All of my troops had moved normally, and no one had spotted an alien yet. After ending my turn I saw the "hidden movement" screen, everything seemed to be working properly I heard footsteps, gunshots, but nothing get hit or die. Near the end of the aliens' turn one popped into view and thats when things stopped. I was unable to move or select my soldiers, couldnt scroll or push any buttons, it was like the game was still processing the end of my turn. After several minutes I just ended the game. So far I havent been able to repeat this error.