Network connection stopping ros subscription

edit

Whilst running the tutorial: http://www.ros.org/wiki/stage/Tutorials/SimulatingOneRobot

I am trying to write a rosjava program that will subscribe to the robots laser data and then publish messages. When I run the program whilst not being connected to a network it runs as expected and prints out a message to show that it is working.

However when I run it whilst connected to a wireless network the program doesn't appear to be receiving any messages and throws the following exceptions:

INFO: Subscriber registered: Subscriber<Topic<TopicIdentifier</base_scan>, TopicDescription<sensor_msgs/LaserScan, 90c7ef2dc6895d81024acba2ac42f369>>>
25-Nov-2012 14:04:37 org.ros.internal.node.topic.UpdatePublisherRunnable run
SEVERE: org.ros.exception.RosRuntimeException: Connection exception: Laptop2012/67.198.168.6:36300
25-Nov-2012 14:04:37 org.ros.internal.node.topic.UpdatePublisherRunnable run
SEVERE: org.ros.exception.RosRuntimeException: Connection exception: Laptop2012/67.198.168.6:36300
25-Nov-2012 14:04:37 org.ros.internal.transport.ConnectionTrackingHandler exceptionCaught
SEVERE: Channel exception: java.net.ConnectException: Connection refused
25-Nov-2012 14:04:37 org.ros.internal.transport.ConnectionTrackingHandler exceptionCaught
SEVERE: Channel exception: java.net.ConnectException: Connection refused

Does anyone know how or why this is happening relating to my network connection and if I can fix it.

I am running Fuerte on Ubuntu 10.04 (Lucid Lynx).

Thanks