Earlier versions of XP came with Java, but when travelling recently I noticed some internet cafe XP boxes without it. I wonder if MS withdrew it after their legal issues with Sun? There are other reasons why problems may occur. Check FoD support pages for ideas, but I do know that Norton Internet Security can mess things up sometimes. It's the "sometimes" which I don't get...
www.java.com for the latest Sun version of Java. Make sure all other versions are uninstalled. I think FoD have a link to a Microsoft supplied version - maybe one of their mods can answer that! After upgrading, clear your browser cache (temp int files, inc offline) before reloading. Hope that helps, if not good luck...