Perhaps another player is creating a design with the same name on the same turn? I'm not sure what effect that would have, given that SE4/SE5 allows only one design of a particular name game-wide, but the problem you're seeing seems like like a plausible effect...
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The Ed draws near! What dost thou deaux?
In a PBW game I designed remote resource gatherers and the next turn the design had dissapeared and I wasted a turn building nothing. In my case it's not due to saving the turn partway through issuing orders as can cause problems.
Hello again. Here are some facts that maybe will ring a bell with someone. The two guys in two separate games are playing with US SEV games. Mine is Canadian. Maybe nothing. Both guys are using Vista. I have XP. One of the players had the Design Name File in use, the other did not.