From time to time we re-organize the vast slim mold colony that is the Ubu Projex website.
It could be that you're following a URL that no longer exists, or that David screwed up the coding on a page. He appreciates finding out. A quick email to him with a report won't go amiss. It never hurts to refresh the browser.
If you are searching for some particular piece of information, or can't find something, or need a question answered, then feel free to email Communex.