A customer (see Comments for details) reports that if a JNLP-launched applet is dragged to the desktop and the JNLP file specifies system properties or (certain?) JVM command-line arguments, relaunching the applet from a desktop shortcut will fail with the following exception:

Starting applet (200x200) with parameters:
  height = 200
  __applet_relaunched = false
  java_arguments =
  width = 200
  code = applet.DragExample
Validating file:/C:/nbWorkspace/AppletTest/dist/AppletTest.jar , version null...
JNLP2Viewer.appletJRERelaunch:
    java_version : 1.6+
    java_arguments : -Djnlp.packEnabled=true
java.lang.Exception: JNLP2Viewer.appletJRERelaunch: 1.6+ ; -Djnlp.packEnabled=true
    at sun.plugin2.applet.viewer.JNLP2Viewer$1$3.appletJRERelaunch(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.fireAppletJRERelaunch(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

The JNLP2Manager is attempting to relaunch the applet when doing so is not supported by the surrounding environment.

The customer's test case (NetBeans project) is attached.