how it should work:

there are 4 wonders that give you a city improvement in all your cities.
these are:
Hagnia Sophia
Internet
National shield
Central Matter Decompiler

when you build (or take a city that has) one of these, all your improvements of that kind
will be sold and you wont be able choose it in the build manager.
however this will first happen in the turn after you get the wonder.
(meaning: you build the damn thing, go to next turn and then the script kicks in)
if you should somehow loose the wonder you will regain the right to build the city improvement.

the file can be downloadet here http://kaan.subnet.dk/