Slitherine

...with plans coming to fruition, when my planned colonization is abruptly put on hold with the following statement filling my turn log with: "Ship being built for colonization can not be constructed (name of planet)". I've got plenty of resources and my population is not revolting, so what's up? The only thing I can think of is that maybe the pirates sitting on a chokepoint might have triggered the warning. Does anyone out there have any ideas? Has this happened to anyone? Couldn't find anything in the game manual so...help, I need somebody...

I saw that this weekend. And yes it was because a Pirate was sitting on the start lane that lead to the planet I wanted to colonize.
I just left the order there so that when I cleared the Pirates the build would continue.