The Netscape 7 is used
(Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.0.1) Gecko/20020921 Netscape/7.0)
 on Solaris 9 (SunOS 5.9 Generic_117171-07 sun4u sparc SUNW,Ultra-30)
with plugin
Java(TM) Plug-in 1.4.2_11-b02 File name: libjavaplugin_oji.so Java(TM) Plug-in 1.4.2_11

Bug was during testing the regression bug 4789981

To reproduce follow instructions below
=====
Load the following page into this browser
     http://jpseuwt-ap/testcases/131/4789981/testcase1/jsJAVA.html
   A page will be loaded with a text field and a button on it
5. Click on the button, and then type
       alert('hi')
   in the text field and click the button again
   A small dialog window will come with 'hi', close it
6. Remove the texts from the textfield and click the button again
7. Click 'Reload' button in the browser to reload the page
8. Follow the steps 5, 6 & 7 again
    If the browser crashes, test FAILED
=====
Browser closed without any notification or message after execution of step8.

I've checked it on 1.4.2u10b3, 1.4.2_fcs - the same. but could not test for 1.3.1 because browser doesn't link the ./jre/plugin/sparc/ns600/libjavaplugin_oji.so from 1.3.1
so it looks like regression anymore - please see related bugs 4789981, 5083638.
Please correct me if i'm wrong.