I'm having the same issue.  I just received my ISY from Smarthome today.  Windows XP Pro SP2, Norton Internet Security 2008.  I can telnet into the ISY just fine, UPnP is fine and the app opens up, but admin/admin login just results in NullPointerException Socket Closed.  I have tried disabling all Norton protection to no avail.  Perhaps I will also have to try fixing the IP address in the ISY. 
  
Thanks, 
Tom