Hi neil and everybody who read this post,

we ran some tests and searched on forum about CB 2.0 and the login methods used.
CB overrides completely the Joomla standard login as soon as installed, so it's mandatory that the CB login module is used to perform a correct login on the site.
This is reported here: http://www.joomlapolis.com/documentation/community-builder/getting-started/18457-turning-off-joomla-login-module

Of course the same affects also InstantFBLogin that uses the same Joomla standards to perform the login using normal username/password. The Facebook login is not affected.

By the way we found a setting in the plugin of CB that allows to continue to perform login also using standard Joomla login module and thus also IFBLogin. In the CB system plugin the parameter 'Redirect URLs' should be disabled as in the following pic.

Regards,

John