I have this error too and its ... incredibly annoying. I downloaded the package from stardock central of GC2 and its two expansions two days ago. I get different, but very consistent, bugs on all of them.

On Dark Avatar, whenever you make a fleet, 95%+ of the time the fleet cannot be instructed to move further than one turn's distance initially. When you click outside one turn's distance away from the fleet, it shows the "moves left" as 4/0, 5/0 etc as the initial poster said. However, they're still there if you If you try to set a waypoint exceeding its movement speed for that turn, the fleet refuses to move or post the waypoint. If you move the fleet FIRST by only moving some of its movement points, you can often then get it to put a waypoint further away, but oftentimes the waypoint has no ETA and disappears once you hit the Turn button. This bug does not occur in the Twilight expansion nor does it occur in the base GC2 game for me.

I lost the Turn button within 10m on the campaign in Dark Avatar. Even loading from an earlier save in the campaign, I still lose the Turn button. On the Twilight expansion, all planets and stars that are clicked show me a message about mining ascension crystals and refuse to give me planetary/solar information.

Thanks, that worked perfectly.