You have tried to access a destination on the internet, and are unable to do so.
Possible reasons and fixes might be:
You may not have internet access. - Your machine is not connected to the internet, and you will not be able to take advantage of URLs, or destinations on the internet.
You may be inside a firewall, and you must specify a Proxy server to HotJava. - Go to the "Options" area on the top menu bar of your HotJava browser and select "Properties". Press the "Firewall Proxy" button, and enter the machine in the first field, and the port (usually 80) in the second field. Contact your system administrator for this proxy information.
After you set a proxy, you will have to press the "reload" button on the bottom of the hotjava browser (the two arrows in a circular foramtion) to go to the URL.