Sometimes , the items or the items disappear and the frame. This also happened on the server with others , and so I think it's a bug. I walked to my chests and saw that the item Frames heard were gone out , the items were scattered on the ground with the item Frames there.
The day before I went to my store ( bukkit server - plugin) and then it was out of the item Frame road was chest above the shop . I went to a friend of mine who said it happened to him.
This bug tracker is only for unmodded versions of Minecraft. And because it is a bukkit server this report will probably get closed as Invalid. If you experience this bug also on an unmodded server please comment here again. You can try to ask the owner of the server or tell him the problem.