If Plug-in is not able to find the requested JNLP, due to any reason it hangs the browser by throwing the following exception. Sometimes browser hangs right away and sometimes it hangs after refresh/reload or page switch.
java.lang.NullPointerException
at sun.plugin2.applet.JNLP2Manager.initialize(Unknown Source)
at sun.plugin2.main.client.PluginMain$StartAppletRunner.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Error while initializing manager: java.lang.NullPointerException, bail out

Steps to reproduce:
1) Load following applet (negative scenario)
http://nicole1.sfbay.sun.com:8080/plugin_tests/JNLPSupport/Liveconnect/html/JSAppletCommunJNLPHostNeg.html
2) If above mentioned exeprience is noticed than bug is reproduced