What's the problem you're having, maybe someone here can help?
IMHO, I can't imagine any readers are going to have profound issues with a blank "author" tag. The issue about a space in a URL is spurious, as the "URL" is in the content of a "comments" tag. RSS readers deal perfectly well with most technically invalid RSS (just like all web browsers deal with invalid HTML.)
They're supposed to be updated whenever a thread is added or removed from the forum; furthermore, the items are sorted according to the date on the first post in a thread. For a low-traffic forum like Groovy, this can lead to noticeable differences between the feed and the forum. If you look at the forum and the feed, you should see that the three most recently-started threads are, indeed, the three that are listed on the feed. While there have been posts since the 25th, there have been no new threads started since then. [ August 30, 2008: Message edited by: Ernest Friedman-Hill ]