Since the 1.1.2 update ( love it btw) things I hold in my hand are dropping to the ground and sometimes blocks in my inventory if I'm using them in my hotbar and also have some in inventory elsewhere they disapear for a few seconds then reappear.
EnviroMine adds temperature to the game and cold stage 1 causes you to drop items, don't know if that is your issue or not as I usually get overheated not cold.
