Client believes there is an instance already running after closing improperly

When the new client is attempting to reconnect to the server, and I click "Exit instead", the client closes but when I try to open it again it says that there is already an instance of the client running, and refuses to open, when there is not one. I can open the client again after manually deleting lockfile, but this is the only way, and most people probably don't have the gall to remove an important-looking file just on a hunch, so a fix would be good.