If the post_style is not set to 1 (Markup) or 3 (Markup and HTML), [url]...[/url] tags won't be converted, and if not 2 (HTML) or 3 (Markup and HTML), HTML will be escaped. It sounds like in these cases the posts are set to Plain text only (post_style = 0).
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com