There are some odd side-effects of using powers in non-standard ways. I made an "observatory" facility using facility picture #38 and the "EM Passive" scanning ability and built it on one of my border-system planets once. It worked, and it continued to work after I scrapped the facility!
I guess there is something similar happening in both cases. A flag gets set and then never gets UNset.
[This message has been edited by Baron Munchausen (edited 26 September 2001).]