OK, now I actually 'bookmarked' the link, I can see what it is.
The error message is to do with pippki.jar file in chrome dir.
Here is the file with the 'fault line' highlighted:
============================================================
<?xml version="1.0"?>
<!--
- The contents of this file are subject to the Mozilla Public
- License Version 1.1 (the "License"); you may not use this file
- except in compliance with the License. You may obtain a copy of
- the License at
http://www.mozilla.org/MPL/
-
- Software distributed under the License is distributed on an "AS
- IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
- implied. See the License for the specific language governing
- rights and limitations under the License.
-
-
- Contributor(s):
- Javier Delgadillo <javi@netscape.com>
- Bob Lord <lord@netscape.com>
- HÃ¥kan Waara <hwaara@chello.se>
-->
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<!DOCTYPE dialog [
<!ENTITY % newserverDTD SYSTEM "chrome://pippki/locale/newserver.dtd" >
%newserverDTD;
<!ENTITY % pippkiDTD SYSTEM "chrome://pippki/locale/pippki.dtd" >
%pippkiDTD;
]>
<dialog id="ssl_warning" title="&newserver.title;"
xmlns="
http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
onload="onLoad();"
buttons="accept,cancel,help"
ondialogaccept="return doOK();"
ondialogcancel="return doCancel();"
ondialoghelp="return doHelpButton();">
<script type="application/x-javascript" src="chrome://global/content/strres.js"/>
<script type="application/x-javascript" src="chrome://pippki/content/pippki.js"/>
<script type="application/x-javascript" src="chrome://pippki/content/newserver.js"/>
<script type="application/x-javascript" src="chrome://help/content/contextHelp.js"/>
<stringbundle id="newserver_bundle" src="chrome://pippki/locale/newserver.properties"/>
<vbox flex="1">
<hbox valign="top" align="center">
<image class="alert-icon" style="margin: 5px"/>
<vbox flex="1" valign="middle">
<description id="intro"/>
<separator class="thin"/>
<description>&newserver.reasons;</description>
<description>&newserver.reason1;</description>
<description>&newserver.reason2;</description>
<description id="reason3"/>
<separator class="thin"/>
<description>&newserver.notify;</description>
<separator/>
<description id="question"/>
<separator class="thin"/>
<vbox flex="1" align="start">
<button id="examineCert-button" label="&newserver.examine;"
oncommand="viewCert();"/>
</vbox>
<separator class="thin"/>
<vbox>
<radiogroup id="whatnow" flex="1">
<radio label="&newserver.remember;" id="remember"/>
<radio label="&newserver.session;" id="session" selected="true"/>
<radio label="&newserver.refuse;" id="refuse"/>
</radiogroup>
</vbox>
</vbox>
</hbox>
</vbox>
</dialog>
===========================================================
It reports an 'illegal entity' on that line, Char 1 = '<'
???
Nick