Any regular users of World Wind or World Wind Java will probably have noticed strange behaviour recently, slow startup, tiles not loading, etc. this is a problem with the NASA servers and seems to be getting worse.
NASA are aware of the issues, and short term fixes are being tried, in the long term we will have to modify the next release to support mirror servers (stepman where are you!), and set up some mirrors outside of NASA for both imagery and elevation data. FEF and NASA are working hard on this so please bear with us, if you are planning any demos I would suggest you set up a big cache and start up your machines early (World Wind can take a while to timeout and stop trying to access the servers).
We are sorry about this trouble, and truly feel your pain, this is really irritating me a lot too.