Problem starting IsaViz the first time.

Hello,
 
I've just downloaded and unzipped/installed IsaViz.  All seemed OK.  I have jdk/jre 1.6 and run other java programs successfully.
 
However, when running run.bat from the command prompt, the initial splash screen comes up and then gets stuck with the following in the command-line window:
 

Exception in thread "main" java.lang.ClassCastException: java.lang.StringBuffer

cannot be cast to java.lang.String

        at org.w3c.IsaViz.ConfigManager.initLookAndFeel(ConfigManager.java:139)

        at org.w3c.IsaViz.Editor.<init>(Editor.java:304)

        at org.w3c.IsaViz.Editor.main(Editor.java:2815)

 
Any thoughts on what could be causing this?
 
Thanks,
 
 
 
Stewart Wallace
Project Manager, Dictionary of Sydney
www.dictionaryofsydney.org <https://mail.cityofsydney.nsw.gov.au/exchweb/bin/redir.asp?URL=http://www.dictionaryofsydney.org> 
61 2 417 420 155