Use Graphics Test available here http://j2se.east/deployment/applets.html to reproduce the problem.

export NPX_PLUGIN_PATH={your_jre}/plugin/i386/ns4 - for NS 4.x on Linux
setenv NPX_PLUGIN_PATH {your_jre}/plugin/sparc/ns4 - for NS 4.x on Solaris
for Netscape 7, you need to cd to the installation directory of your Netscape 7 browser. From there cd to plugins directory. Create a softlink (or replace existing one) libjavaplugin_oji.so which is linked to {your_jre}/plugin/i386/ns610 - on Linux
{your_jre}/plugin/sparc/ns610 - on Solaris

Start the browser (Netscape 4.x or 7).
Visit the page with Graphics Test applet.
When applet loads, click on the Choice component. Browser crashes.

If you happened to use jre, you'll see no error logs or core file. If you are using plug-in that comes with JDK, you'll see core file and hs error log file generated.

Described behavior happens on Linux. On Solaris, if you were to follow steps above, it would cause the following exceptions in the Java Console:
java.lang.AbstractMethodError: java.awt.Window.getTemporaryLostComponent()Ljava/
awt/Component;
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFoc
usManager.java:544)
        at java.awt.Component.dispatchEventImpl(Component.java:3509)
        at java.awt.Container.dispatchEventImpl(Container.java:1627)
        at java.awt.Window.dispatchEventImpl(Window.java:1599)
        at java.awt.Component.dispatchEvent(Component.java:3480)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:451)
        at java.awt.SequencedEvent.dispatch(SequencedEvent.java:93)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:449)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:201)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:151)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)


This was not happening in promoted build 06. It is happening in the nightly build from November 17. Do not have an earlier build available to find out exactly when this started to happen. I saved rpm bundles from build on November 17 locally - let me know if you need them.