When I want to pose a painting on a wall, the first one disappear. Then, the next ones I pose appear a fraction of second before disappearing too. If I quit my game and come back, all the paintings are placed on top of each other. After searching a little, it seems that this bug is there from pre-releases of Minecraft 1.5.
Duplicate of MC-11236, please use the search function to see if your bug has already been submitted. Currently over 54% of tickets are being closed as duplicate.