This error has only happened a few times, but in one instance I designed a ship, saved it, but could not select it from the list to build it on a planet (it did not appear in the list) However, when I tried creating it again and saving it, it told me I coudl not duplicate the name. I tried saving it under a different name, with the same problem. AT a later point both deisgns showed up. I had gotten the next minituarization tech at that point so I think it might be related, although I've never seen this error again, it prevented me from building my Advanced Troop Transport at a crucial point in the game.
