This issue is pretty much described in the title. I turned off the autocast for the colonize ability on my colony ship so I could jump past a dead asteroid to get to a more valuable planet, but my ship stopped and colonized the asteroid anyway. This seemed to be a consistant problem for me during the whole game, with no specific triggers to initiate the behavior. I have yet to play more than one game to verify if this happens every time with every race or if it was a freak occurance.