I did the run.bat and when it started here's what it said C:\Users\Nick\Desktop\bukkit>java -Xmx1024M -jar craftbukkit-1.6.4-R1.0.jar -o t rue 16:13:41 [INFO] Starting minecraft server version 1.6.4 16:13:41 [INFO] Loading properties 16:13:41 [INFO] Default game type: SURVIVAL 16:13:41 [INFO] Generating keypair 16:13:41 [INFO] Starting Minecraft server on *:25565 16:13:42 [WARNING] **** FAILED TO BIND TO PORT! 16:13:42 [WARNING] The exception was: java.net.BindException: Address already in use: JVM_Bind 16:13:42 [WARNING] Perhaps a server is already running on that port? > I don't have a server running right now. Can anybody help?!
Looks like your computer / internet is using port 25565. Go into server.properties and change the 25565 to a lower number. Then try. Also others can't connect to you unless you port forward (http://portforward.com)
I'm guessing he still has an instance of bukkit/MC running. Something is listening on that port, and nothing should be. Try opening task manager and look for a java process running MC and kill it. Or just reboot.