Sometimes reproducable when relogging after server restart. Character is able to open and close doors, punch (visible) zombies and environment. Didn't try on players ;). No interaction possible with any item except glowsticks (can be broken outside of inventory). Character stats seem to be "frozen" in their initial condition. So no hunger, thirst, freezing or damage from falling. Character is completely invisible to other players and zombies (visible and unvisible). Voice chat doesn't work / players do not react. Mouse wheel menu always shows options "hide body" and "inspect contents" .