Steps to reproduce:
1.On Mercury10, Mozilla1.4(2003/9/28),jre1.4.2_02
2.Set proxy ebay,launching http://sqeweb/deployment1/mantis_ws_plugin/doc/proc/JPI_OJI.html#Test%20Cases
select (#SF-6) ScriptRedesign J2JS.html.
3.After auto test begin excute three or more test pages, hit back button to go back to the former called test page.
4.Sometimes mozilla close itself without any cue on console,sometimes the java console became gray and disable, even can't be closed.