one more thing you should mention, don't put people(or items) on top of roof's.
check the green roof on the village map to see what I mean.
also, using firefox and can see the images clearly. try waiting for the page to load fully, and if that doesn't work, press f5.
only other thing that might work is holding the alt. key and pressing f4, but only if it's an I.D.ten T. error.