Just did some quick testing with FF and when clicking rapidly a big distance away I was able to get the out-ofsync error. However I had to click at lest 3-4 times rapidly at the spot I wanted to go to. It seems like the last click goes through after the map has centered back on the unit to start the move, and then it gets another path, aborting the current move-order.
I´ll look into fixing this, but for this particular case Im experiencing I think I need to click at lest 4 times in a row, the first 2 clicks sets the path and starts the move, then the screen is centered back on the unit (to start the move), and my next 2 clicks then accidently gets applied on the current part of the map, i.e. close to the unit, and gives it another path+moveorder.
Is it possible this is the same thing that happens to you, or is it just a fast double-click that you do? (not 3-4 clicks)