I experienced an issue after placing a fireplace in a house fireplace where my inventory and hotkeys became unresponsive. After about 5 minutes of playing around I was able to resolve the issue by tabbing out and back into DayZ. The Steam overlay apparently had "ghosted" meaning after placing the fireplace, somehow, Steam overlay was activated but was not on my screen. The overlay was preventing the game from seeing any command that was inputted. After tabbing back into DayZ the Steam overlay was again visible, I was then able to exit the overlay and continue playing DayZ as normal. I DID NOT manually access the overlay when the issue occurred, it happened all on its own.