I think your problem is Kaffe. It seems everyone has Kaffe installed lately. :-) Kaffe is an open source version of Java that implements (mostly) Java 1.1, which is an older version of Java. You didn't post your system details so I'll assume you're on an rpm based system. Open a terminal and type:

rpm -q kaffe

That'll check your rpm database for kaffe. If it's installed and if you don't really, really want it. Remove it by becoming the root user and typing:

rpm -e kaffe

I'll assume you have a 1.3.1 version of Java installed and correctly added to your PATH variable.