FOSS gamedev and creative worlds

Please help.
This was the error message.
Ubuntu 12.04 LTS 64_bts

You already have one instance of minetest running - it's probable that a previous run crashed or locked up but never fully closed. Look in your process list/task manager and kill off any others, then try again.

You might also have another application/service using port 30000, which is the default port for the Minetest server. Try running "sudo netstat --tcp -l -p" to see what program is already using port 30000. This should quickly tell you whether it is another instance of Minetest or something else entirely.

If you're playing singleplayer, it's actually port 30011.

To quickly see any other instances of minetest, run "ps aux | grep minetest". Kill them with "killall minetest".