Game keeps getting stuck on units

[simwiz2]

When a unit runs out of moves, or is fortified, etc then the screen is supposed to go to the next unit automatically. Recently when i move a unit, it will remain selected, with moves 0/X remaining, and i will have to click on another unit manually to unselect it. This can happen many times in one turn, and considering the amount if units in the industrial ages is a real nuisance. also, if it happens to a worker i have to restart my computer, though all the other units get "fixed" just by activating another unit.

So does anyone know how to fix this?