BT Social Login module
The only login module that CB supports is its own.
The problem was once a user registered, activated his account and login everything was ok but after logout couldn't login back again and had to change the password through the email process to be able to login again.
Ensure you've latest Joomla 2.5.x and CB 1.9.1. If issue still persists enable debug mode and maximum error reporting in Joomla global configuration. Once done retest and see if any fatal errors are present as there are known issues with Joomlas new password crypt feature and some servers.