Actually, I gave up and started again with a known working 7th Fleet box.
Everything was fine this time. For a while. Then just as I added the last part, it now part loads, and then crashes, reporting:
version 1.2.1.14
os Microsoft Windows NT 6.1.7601 Service Pack 1
framework 2.0.50727.8762
cpu count 2
System.NullReferenceException: Object reference not set to an instance of an object.
at ZunTzu.Visualization.y.c.e()
at ZunTzu.Visualization.y.b(Int64 A_0)
at ZunTzu.b.b(String[] A_0)
I can only assume that the gamebox is jinxed
P