Logging out the user do not reset esd running on the client, so no other user is able to play sound. You can test this by copying the .esd_key file around to the other users and see if they can play sound on the given client.
When I copied .esd_key file from user4 to user1, sound started working again for user1 on terminal-3.
After deleteing user1's .esd_key file, no one is getting sound on terminal-1. User1 was the first one to log on to this terminal and getting sound here.
OleA