I have update his thread after found the solution, that is in the first answer.

Hi

I have installed this great forum in my domain using 3.5.1 version. SSO plugin is enabed too in order to use my own user/password database.

After login into my site and follow "forum" link... codoforum must "login atuomatically" into the forum.

The first time that user enter in the forum (when user dabatase is filled with this "new user data" from SSO, everything works fine, but after that, in the second atemp to enter into the forum it's imposible if I'm not using Safari.

Everything works like a charme with Safari browser (mac) but if I try to access using Chrome, Firefox (in mac or windows) and even Edge in windows... it allways reload the page trying to "login" once and another time in a loop.

If I disable SSO pluging, manual login also works only under Safari... with the other browsers even if the user/pass is correct no warning is showing and "clean" the form to put the user/pass again.

If I delete the "field" about this user in "users table" (into the database) It works for the first time in all the browsers.

I guess that both situations have a relation ...

Any idea about what is happening?

I have the same problem trying to access into admin, ony works with safari most of the times.

Thanks in advance!

SOLUTION: there were a conflict between my website sessions and forum sesions