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.