Solved Direct accessing the kunena component and permissions.

I just don't understand why this is not working right!

You say that you have not made any changes to the original .htaccess file (created by renaming htaccess.txt -> .htacess); you say that you do not have any 3rd-party SEO; you say that you have completely emptied the Joomla menu trash, and yet you still have a duplicate URL alias hanging around somewhere that is causing this page redirection problem.

Well, I'm sorry, but I have no idea what's going on behind-the-scenes. This is bizarre!

Sounds like there's a web proxy (or some other redirection barricade) getting in the way before the HTTP GET request hits Joomla. That's just my guess.

Thank you for allowing me the opportunity to examine your administration site. After spending over an hour, I cannot figure this out.

Accessing the site works find if you use SEF URLs. Everything else falls apart, as far as Kunena is concerned, if you try to use non-SEF URLs. I am fairly sure that the FLEXIcontent menuing system has something to do with this but I don't know anything about FLEXIcontent and therefore I cannot say any more about this.

I don't know what to advise in this situation. As far as I can tell, everything looks the way it should look for a standard Joomla installation. The only additional factor seems to be the FLEXIcontent menu system.

Your website works - if you use SEF URLs. It even works if you use non-SEF URLs (you just get a warning message). In fact, if you turn off Joomla debug, the warning message disappears. So, if I were in your situation, I would not worry about this.

Thank you very much for the time you dedicated me!

If this error reoccurs, I will ask in their forum.