@fede:
The 'out of sync' msg is about an alien trying to move. Did you try to move your soldier during the alien turn or yours ?
I was in my turn when my soldier didn't move. When he didn't react on the fly i was guessing the bug about reaction fire that makes aliens move in my turn, i'm really used to experience this very often. In a hurry i might have clicked again (when aliens *coul've been moving* IN MY TURN) and this caused crash.
So no, it was my turn, but the other bug (IF it really happened) could've mixed things up.
Edit: i'm even more convinced that i moved in alien's robbed turn. There would no other explains why my unit didn't move, unless that bug occurr.
Server crash happens by moving in enemy turn for sure. More info next crash!