Item Frames Dissapear or the Items in the frame

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.