See, for example, the attached stack trace. The relevant part is here:

    "Screen Updater" (TID:0xed9d84a0, sys_thread_t:0xecd71de0, state:CW) prio=6
        java.lang.Object.wait(Object.java)
        sun.awt.motif.MDialogPeer.show(MDialogPeer.java:104)
        java.awt.Dialog.show(Dialog.java:220)
        java.awt.Component.show(Component.java:498)
        java.awt.Component.setVisible(Component.java:460)
        sunw.hotjava.security.BagDialog.handleDialog(BagDialog.java:143)
        sunw.hotjava.security.SecurityDialog.askAuthorization(SecurityDialog.java:155)
        sunw.hotjava.security.SecurityDialog.getAuthorization(SecurityDialog.java:113)
        sunw.hotjava.security.SecurityDialog.getPropAuthorization(SecurityDialog.java:210)
        sunw.hotjava.security.PolicyMedium.checkPropertyAccess(PolicyMedium.java:127)
        sunw.hotjava.security.SecurityPolicy.checkPropertyAccess(SecurityPolicy.java:284)
        java.lang.System.getProperty(System.java)
        jclass.util.JCEnvironment.getJavaVersion(JCEnvironment.java:167)
        jclass.table.Draw.<clinit>(Draw.java:272)
        java.lang.ClassLoader.loadClassInternal(ClassLoader.java)
        jclass.table.TraverseInitial.traverse(TraverseInitial.java:183)
        jclass.table.TraverseInitial.traverse(TraverseInitial.java:118)
        jclass.table.JCTableLite.reshape(JCTableLite.java:1521)
        java.awt.Component.setBounds(Component.java:889)
        java.awt.GridBagLayout.ArrangeGrid(GridBagLayout.java:1256)

Screen Updater has Component.LOCK, and it's trying to post a modal dialog.
The code in MDialogPeer creates a thread and blocks on it, and that
thread waits for Component.LOCK.

The problem (at least for Solaris) is the code in MDialogPeer:

        if (((Dialog)target).isModal()) {
            ModalThread mt = new ModalThread(this);
            synchronized(mt) {
                try {
                    mt.start();
                    mt.wait();
                } catch (InterruptedException e) {
                }
            }

The current thread (which holds Component.LOCK) is waiting on the
ModalThread, but ModalThread immediately requests Component.LOCK.

See suggested fix