When java is configured to use my browser's proxy configuration, and my Firefox prefs.js file has more than 197 user_pref() entries, javaws dies on startup, as follows:

itcto-sxsr-2:~ % /usr/jdk/jdk1.6.0/bin/javaws -viewer
itcto-sxsr-2:~ % java.lang.NullPointerException
        at java.lang.System.arraycopy(Native Method)
        at java.lang.String.getChars(String.java:855)
        at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:391)
        at java.lang.StringBuffer.append(StringBuffer.java:224)
        at com.sun.javaws.Main.addToSecurityProperty(Main.java:1060)
        at com.sun.javaws.Main.initializeExecutionEnvironment(Main.java:1013)
        at com.sun.javaws.Main.continueInSecureThread(Main.java:169)
        at com.sun.javaws.Main$1.run(Main.java:106)
        at java.lang.Thread.run(Thread.java:619)

itcto-sxsr-2:~ %


If pointed at a URL for JNLP, it shows the "Java Loading..." splash for some seconds, then quitely exits with no error message.