It could be some kind of cookie problem, based on what you just said. Perhaps your computer/browser is somehow not letting the cookie be deleted, or there's a duplicate that is being ignored. The best way to find out would be to just delete all of your cookies.
This will mean that you'll need to log in with all your usual haunts again, but it should slaughter any and all problems of this kind. Also, be aware that browsers treat cookies set on lucasforums.com and www.
lucasforums.com as two separate sites, so try logging out on both 'versions' to see if it helps.
We should probably set up a htaccess that enforces the www really, though that'll probably simultaneously log out at least 50% of the forum.