I'm using WordPress to set up a relatively basic website for my homeowner's association, at http://www.vantagehoa.org - it consists of a handful of pages, some of which redirect to a phpBB 3.0 installation for a forum.
For some reason, if I go to any page that does not exist, it very briefly displays a page that appears to be a combination of a handful of the pages on the site, and then it redirects to the forum - I suspect that's because one of the pages it's displaying is the "discussion-forum" page, which consists of only an HTML redirect (meta http-equiv="refresh"...).
I thought perhaps it was something with my theme, which is a very basic custom theme, but when I reverted to the default theme, which has a built-in 404 page (as does my theme), the problem persists, so it's apparently theme-independent.
I have a couple of WordPress installations running on another host, and neither of them have this problem.
Any clue what is going on here and what I can do to try to fix it? Again, I tried reverting to the Kubrick-based "WordPress Default" theme and the problem persisted, so my theme is not at fault here.