The very obscure "planet vanishing" bug is becoming more prevalant, perhaps because I'm using Fyron's Quadrant Mod and TDM Mod Pack races more and more.
I was building ringworlds in a 5 star system. One for each enemy race so they'd have a place to live when I wiped the galaxy clean of their empires -- and one ringworld just vanished.
[EDIT]
Link no work. Arkcon is
To see the thread, do a search for author Arkcon and "planet vanishing". The thread was started by "Q", but you can't use his handle in the author field.