Issue appears as result from a conflict with one of your installed extensions. Please see summary of issues that need be addressed; some have already been addressed by me.

Your first time login and terms & conditions links were incorrect, this has been fixed.

You then have cbtwitter (cbtwitter) installed which conflicts with our cb.twitter (CB Twitter) plugin. Please pick one and remove the other.

Onto your issue of user=0; you've a plugin called store (CB Store) installed that is incorrectly built; it is resulting in the redirect. This plugin has been disabled and logins now function perfectly fine. If you intend to enable please debug for your self or contact the developers. We do not assist in repairing 3rd party extensions.

In addition to this what 3rd party extensions you have installed that have placed "CB" in their names and are NOT developed by us are in disagreement to our CB API guidelines; this is misleading to users in believing WE developed the extension which we did not. Please advise this to the developers of such extensions, thank you.

Please be aware you have a massive amount of extensions installed. I recommend reviewing what is installed and only using what is absolutely necessary. The more installed the more likely you'll have a conflict of some sort.

Also please keep in mind this was discovered by following the exact debug procedures outlined in my signature. For future reference please perform Help Us Help You "word for word".