Run
    javaws http://javaweb/~nn136682/JVMArgumentTest/system_property.jnlp

Will sometime get this error in trace and applet does not show.

ui: Attempt to switch toolkit mode after initialization to mode: 1
java.lang.ClassCastException: com.sun.deploy.uitoolkit.impl.awt.AWTPluginUIToolkit cannot be cast to com.sun.deploy.uitoolkit.impl.awt.UIToolkitImpl
    at com.sun.deploy.uitoolkit.impl.awt.UIToolkitImpl.changeMode(UIToolkitImpl.java:152)
    at com.sun.deploy.uitoolkit.ToolkitStore.setMode(ToolkitStore.java:271)
    at sun.plugin2.applet.viewer.JNLP2Viewer.main(JNLP2Viewer.java:70)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.sun.javaws.Launcher$2.run(Launcher.java:2117)
    at java.lang.Thread.run(Thread.java:722)

This exception is catched and ignore, however the applet was not showing.