Here are all the threads I can find about your problem
http://www.gnutellaforums.com/showth...tialize+plugin http://www.gnutellaforums.com/showth...tialize+plugin http://www.gnutellaforums.com/showth...tialize+plugin
The consensus seems to be that it's a Java problem! Try uninstalling your Java (thru add/remove programs) & reinstall it using the offline installer here
http://www.gnutellaforums.com/showth...threadid=50931 
**Replies to posts aren't working at the moment.
Reply by PM will work. You'll see an error page but the message still goes through.
Else, start a new thread titled "your original thread - merge".
A moderator will merge threads when they get the chance.