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I think your problem might come from strict domain binding and absolute forum address. By that, I mean that www.den4b.com/forum is not the same as den4b.com/forum when were are talking about sessions and cookies.
You're right, Denis. However, no other forum seems to have issues with me typing SiteName.com/forum, then logging me successfully on the very first try into www.SiteName.com/forum. Maybe there's some server-side code that automatically redirects all users who enter SiteName.com in the browser to www.SiteName.com, so that they don't face such issues? Or else maybe the login code shouldn't be so strict, and handle logins properly when both www is provided, and when it's not. Clearly, this sounds like some overtly specific login code on the part of FluxBB. Maybe they can be informed about this bug and can fix it sometime (hopefully soon)?
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