Have a look through the threads below, see if anything helps. Changing skins maybe?
http://www.gnutellaforums.com/showth...ght=font+small http://www.gnutellaforums.com/showth...ght=font+small
If that's no good, make sure your Java's up to date. Use the offline JRE installer here
http://java.sun.com/javase/downloads/index_jdk5.jsp
Remove your current Java version before you install the new one.